Loading...
HomeMy Public PortalAboutYellow Pine Mining DistrictS. #1 COOKRO, SILBERMAN, BERGER IDAHO Figure I. Location map, Yellow Pine mining district. Introduction Numerous Au, W, Sb, and Hg mines and prospects occur in the Yellow Pine mining district in north - central Idaho (Fig. 1). Many of the W, Sb, and Hg mines and prospects contain anomalous concentrations of gold. The major gold producers have been the following: Yellow Pine Mine (1938 -1945) Cooper (1951) Meadow Creek Mine (1932 -1937) Cooper (1951) West End Mine (1982 -1985) Wolford (oral comm., 1986) 256,000 oz Au 1,500,000 oz Ag 68,500,000 Ibs Sb 17,300,000 Ibs W03 49,500 oz Au 168,000 oz Ag 7,000,000 lbs Sb 66,000 oz Au 30,000 oz Ag Most of the Hg from the district was produced at the Hermes Mine (Fig. 2) and consisted of 15,800 flasks (Minerals Yearbook cumulative data). Anomalous concentrations of Au occur at the Fern mine (Fig. 2), which produced only a few flasks of Hg. This study of the Yellow Pine mining district (Figs. 1 and 2) began in 1981, as part of the Challis 1 °X 2° quadrangle CUSMAP (Conterminous United States Mineral Assessment Program) project. The first author's primary responsibility has been to study the occurrence and resource potential for tungsten in the Challis quadrangle. Silberman and Berger studied the West End gold mine (Figs. 2 and 4) and carried out a reconnaissance geochemical survey of the district in 1984. Information from both the tungsten and gold studies is combined in this paper. �X -] 1 . . j, YELLOW PINE REINING DISTRICT Prominent deep - crustal, northeast - trending fault zones (Fig. 3) predominate in the Yellow Pine district; they probably are related to the inferred trace of a Cretaceous subduction zone several kilometers to the west, near Riggins, Idaho. Au, W, Sb, and As concentrations occur within these basement fault zones due to deep circulation of hydrothermal fluids (Fig. 2). Metal concentrations are localized within the faults in granitic rocks of the Idaho Batholith and metamorphic rocks included in the batholith. The host granitic and included metamorphic rocks were brecciated and altered in a series of events. Locally, the rock has been brecciated at least four times. Within brecciated zones, the rocks are strongly altered to clay and sericite and are permeated with secondary quartz. Arsenopyrite ( ±gold) occurs primarily in quartz, albitic plagioclase, and adularia veins; i; is also within fractures of primary grains of microcline and sericitized plagioclase. S- ibnite forms massive replacements of a calcareous metamorphic rock at the Yellow. Pine Mine, the only place in the district where it occurs in significant quantities. Stibnite also occurs within epithermal quartz veins throughout the district. Constituent elements of scheelite and stibnite were transported by fluids that deposited epithermal quartz veins. Scheelite is present within quartz of near - surface, low- temperature origin, including colliform bands and epithermal quartz veins. Scheelite also occurs in clear quartz that is only present surrounding metamorphic quartz and probably formed as a result of its recrystallization. An important control on the process of tungsten metallization is the presence of carbonate. Calcite remobilized from calcareous metasediments and, to a lesser extent, calcite within the metasedimentary inclusions, act as host to scheelite. The metamorphic and clear quartz grade into and are cut by epithermal quartz. Tungsten also occurs in strongly anomalous concentrations (200 -1000 ppm) within jasperoids at the Fern Mine. Arsenopyrite, scheelite, and stibnite were deposited together in overlapping stages of metallization; arsenopyrite deposition began first, scheelite deposition was intermediate, and stibnite deposition continued later than deposition of the other minerals. Regional Geology The Cretaceous Idaho Batholith and metamorphic inclusions or large roof pendants of calcareous rocks, schist, quartzite, and metavolcanic rocks of either Precambrian (Leonard, iYz Hobbs and Cookro (in press)) or Paleozoic (Ross, 1934) age are dominant rock types of the region. Pegmatitic and aplitic dikes and quartz veins common in the district are also Cretaceous in age (Armstrong, 1975, Snee and others 1985). Tertiary felsic to diabase dikes (Leonard and Marvin, 1982 [19841) are also common. The Thunder Mountain cauldron complex, composed of Tertiary intrusive and extrusive rocks, is to the east of the district (Fig. 2). Idaho Batholith lithologies within the Yellow Pine district are either biotite granodiorite, or porphyritic granodiorite, or muscovite - biotite granodiorite and granite, or leucocratic granite. Fresh biotite granodiorite is mottled black and white, medium to coarse grained, and equigranular to porphyritic. Major minerals are sodic to intermediate plagioclase, quartz, microcline, biotite. Apatite, epidote, sphene, zircon, allanite, beryl, and opaque minerals are accessory minerals. The porphyritic granodiorite is composed of coarse- to medium - grained groundmass containing large (5 -10 cm) megacrysts of generally pink poikilitic microcline. The poikilitic microcline contains anhedral plagioclase, quartz, and biotite; these included minerals are randomly oriented and some have eroded margins. Plagioclase within the porphyritic granodiorite, both within megacrysts and adjacent to microcline crystals, is embayed by metasomatic processes. Sodium metasomatism is evident as plagioclase veining and anhedral plagioclase grains with randomly oriented quartz and some K- feldspar inclusions. In areas of Na- metasomatism, plagioclase makes up 90% of the feldspar in the rock. The muscovite- 579 45 I COOKRO, SILBERMAN, BERGER 0, ? 70 MILES 0 5 10 15 KILOMETERS T9 1 , N 4 I ELK CITY QUAD CHALLIS QUAD. mu K� Kgmt •Ta. mu Kim t Tv K,' 21y 4 )< Kim mu SKI . Kim 1110 Ole 12 . mu u Kgd Tv 7 ROCK DESCRIPTIONS Challis —1 —rvics vPink gramt< and quart: monzanfre -Tdc Dionne complex r/f Tertiary dikes Klg Leurocratic granite `' Kg Muscovite btotfle grandodionte and granite Kpd Brwite grandodiorite .i Kgdp Porpirtienic biotfte grandodioritr and granite Kim Mixed rock Kgmf Foliated quartz monronite Idaho batholith undiNerentiated ED Metamorphic inclusions ivithfn the batholith of uncertain age Velfoopine Mining District Fast Kim I Mapping h..m Mnchelf. V E and Bennett. E H. 11979,. and Fisher. F S Mtlnn,.i D H and Jnhnson K M.(14H31 mu Kgdp f Td, Kgd�p1')R It _ Kgd Kgd p mu KgdpTdc mu Hrlated mmeraluaoon along the nosh to north -east trending faults Werd_h." Prospect IC-. Au. Zn. Pb. Ag. Sb W) 2 McRae Mine Red Bluff Mme (W, Zn. Pb. Cu. Ag) Neu Sno hnd Mine (W. Zn Pb Cu. A91 :3 Independence Prospect IF Au. Zn. Hg. Pb. Cu. Ag. Be. W) 4 Annmom Rainbow. Mme IC.. Sb. W Au) 5 Golden West Mine (Sb. W. Auf 6 1 udwig Depus4 IPb. Zn. Cu. Au. Ag W Sbi 7 Wilson Group IAu. Zu. Ph. Sb Cu. A91 H Quartz Creek Mme (W. Sb. Au Ag) 9 Golden Gate Occurrence IAu. Ag. W. Shl 10 Yellow Pine Mine f W. Sb. Au, Ag Hg) 11 Sufbde •10 prospect (W) 12 Meadow Creek Mine IAu. Ag, Sb. Cu. Mu) 13 West End Mme (Au) 14 Hermes Mrne fHg. As. Sb) 1S Fern Mine IHy 16 Mule Train ("14 ", IA- Ag Cu Ph. W) 17 Mein Blur Mine IAu F WI Figure 2. Regional geologic ma northern bordrr p of the Yellow' Pine mining district and vicinity. The open circle on the of the district is the town Of Yellow Pine. Description of Map Units Rock descriptions are largely extracted from Fisher and others, (1983) for the Challis uadran 1 Mitchell and Bennett (1979) for the Elk City quadrangle and Leonard (written Comm., 1986) for the Yellow Pine district itself. These descriptions have units contained in Figs. 2 and 4. q g e and Qd MAINLY GLACIAL DEPOSITS AND ALLUVIUM (Quaternary) - -Includes mill taili Meadow Creek and talus and landslide debris ngs along Tv CHALLIS VOLCANICS (Eocene) —Units include rhyolite, latite, ruff, megabreccia, and rhyolite tuff 580 YELLOW PINE MINING DISTRICT Tg PINK GRANITE AND QUARTZ MONZONITE (Tertiary) — Hornblende, granite, and granophyre Tdc DIORITE COMPLEX (Tertiary) —Suite of non - porphyritic diorite to porphoritic granodiorite characterized by hornblende, euhedral biotire, and magnetite which make up < 35% of the rock. Where present, phenocrysts are zoned plagioclase and pale -red perthitic microcline (up to 1 cm in length). Quartz phenocrystsare rare, rocks weather to chocolare -brown soil Td DIKES OF INTERMEDIATE COMPOSITION (Tertiary) Ki IDAHO BATHOLITH UNDIFFERENTIATED (Cretaceous) Kim MIXED ROCK (Cretaceous)— Includes rocks that range in composition from biotite granodiorite to alaskite (or leucocratic granite) phases of the Idaho batholith along with included metamorphic rocks (described below as mu, muq, and muc) Klg LEUCOCRATIC GRANITE (Cretaceous) —Light -gray to white, fine- to medium - grained granite having distinctive anhedral texture. Principal minerals are quartz, K- feldspar and plagioclase f garnet t minor (<2 %) biotite. Feldspars are altered to sericire and small flakes of muscovite. We believe some of the fine - grained aphanitic 'leucocratic granite" or "alaskire" has an altered texture due to hydrothermal alteration along the north- to northeast - trending faults, biotire has been leached out and secondary silica has been introduced Kg MUSCOVITE BIOTITE GRANODIORITE AND GRANITE (Cretaceous) —Gray to light -gray, medium- to coarse - graained, equigranular to porphoritic granodiorite; contains books of muscovite that are visible in hand specimen and make up as much as 5% of the rock It is considered by Fisher and others (1985) as the younger "core" of the batholith. Note a vague alignment of this unit along the north- northeast faults Kgdp PORPHYRITIC BIOTITE GRANODIORITE AND GRANITE (Cretaceous) — Coarsely porphyoritic granitoid rock containing metacrysts of pink microcline 3 -10 cm long in medium- to coarse - grained matrix containing equal amounts of microcline, plagioclase, and quartz with 5 -15% biotite t hornblende Kgd BIOTITE GRANODIORITE (Cretaceous) —Gray to light -gray, medium -to coarsegrained and equigranular to porphyritic rock. Plagioclase (Au22-30) quartz and potassium feldspar are the major minerals with biotire and rare hornblende. This unit is the dominant rock of the Idaho batholith. Locally intruded by alaskire and small dikes of aplite and granite pegmatite Kig GARNET - BEARING BIOTITE GRANODIORITE (Cretaceous)— medium to coarse - grained, commonly with a somewhat curly foliation. Garn,*is sparse; muscovite is rare; sillimanite, present locally, is microscopic. Locally intruded by alaskire and granite pegmatite Kgmf FOLIATED QUARTZ MONZONITE — (May be Precambrian in age) mu METAMORPHIC INCLUSIONS WITHIN THE BATHOLITH (Precambrian or Paleozoic) —These undifferentiated rocks have disputed ages. They have been described both as Paleozoic and Precambrian, Larsen and Livingston (1920), Ross (1934), Shenon and Ross (1936), White (1945), Leonard (1973). The most recent description is by Leonard (written comm., 1986): The Yellou.jacket Formation in the Yellow Pine area is broadly divisible into three parts. In ascending order these are (1) argillite - siltite unit, several thousand feet thick, base not exposed; (2) carbonate unit, thickness perhaps 150 -750 m (500 -2,500 ft); and (3) metavolcanic unit, thickness perhaps 150 -600 m (500- 2,000 ft). Prebatholith deformation, syn- batholith deformation and metamorphism, faulting, regional strain, and younger blockfaulting leave thicknesses in doubt and require descriptions of the Yellowjacker in metamorphic terms. The argillite - siltite unit is composed of alternating laminae of argillite and siltite, commonly gray to black, locally green, slightly calcareous, with some thin beds of massive argillite and quartzite. Carbonate rock includes marble with disseminated diopside, epidote, or phlogopite; tremolite schist, locally diopsidic. Amphibolite, and a trace of metamorphosed welded rhyolite ruff are present in the medium -grade metamorphic zone. Amphibolite and felsic biotite hornfels are common in the high -grade zone; remnants of welded tuff and volcanic breccia are rare. The Hoodoo Quartzite is a massive, fine- to medium - grained very light colored quartzite. Feldspar, mostly microcline and orthoclase, but with different amounts of albite, ranges from 5 -10 percent of the rock, and muscovite, sericire, and chlorite may range from 0 -10 percent muq WHITE QUARTZITE —early pure, locally with a little biotite. Includes coarse conglomerate of Sugar Creek, Cinnabar, and Fern areas muc LIMESTONE, DOLOMITE, SKARN, SCHISTS AND METAVOLCANIC ROCKS — (biotite hornfels and biorite- quartz - feldspar schist) WE Er COOKRO, SILBERMAN, BERGER biotite granodiorite and granite are identified in the field by the presence of books of muscovite rather than single flakes. It is considered (Fisher and others, 1983) as the younger core of the batholith. This youngest unit of the batholith at the surface (note on Fig. 3) crudely aligns along or is on strike with the northeast - trending regional faults. Because the faults were active during the Cretaceous, rocks that were emplaced as later phases of the batholith probably coalesced along the faults. The leucogranite is light -gray to white, fine to medium grained with a distinctive anhedral texture. Some of the leucocratic granite in the western part of the Yellow Pine district (dashed lines on Fig. 2), is actually altered rock of the batholith. The leucocratic unit crops out on the Deadwood -South Fork of the Salmon fault, which is also called the Johnson Creek fault, and altered rocks of the batholith commonly occur in the region. Aplite and pegmatite dikes and segregations related to the Cretaceous batholith are abundant, particularly in the vicinity of the Yellow Pine Mine. The dikes consist of fine to coarse, subhedral to anhedral grains of K- feldspar, quartz, and plagioclase. K- feldspar phenocrysts, incorporating earlier plagioclase and quartz, are present in the pegmatite dikes. Biorite, muscovite, and beryl are present in places. The aplite and pegmatite dikes are fractured and veined with quartz and calcite. Blocks of metamorphic rocks within the batholithic terrane (Cooper, 1951) are quartzite, mica schist, marble, and skarn, and according to Leonard (unpub. data, 1985) include argillite- siltire, carbonate, and metavolcanic units. At the Yellow Pine and West End mines, metamorphic pendants are composed of andalusite phyllite, staurolite -mica schist and 116° 45 r 114` Y PANTHER CREEK 1 V 2 GRABEN N THUNDER MOUNTAIN O ~ CAULDRON O J COMPLEX i I I i VAN HORN PEAK CAULDRON COMPLEX TWIN PEAKS / CALDERA KNAPP CREEeGRABEN" OChallis GJ OStanley ^EXPLANATION '^ FAULT — Bar and ball DEER PARK FAULT 7( on downthrown side; a BEAR RIVER FAULT arrows show lateral movement 0 t0 10 MMES - - -- — — - 0 10 :0 [00METERS Figure 3. Map of the Challis I OX­ quadrangle showing principal faulrs, grabens, cauldron complexes and caldera, from Kiilsgaard and Lewis ( 1985) with the addition of the Meadow Creek fault zone. 582 YELLOIY' PINE MINING DISTRICT sillimanite - biotite schist, and a marble unit that consists of calcite, quartz, phlogopite, tremolite, and garnet (Fig. 4). The skarn is intercalated in quartzite sequences. Minor amphibolite is included within this sequence. A good exposure of amphibolite occurs along the access road to the Yellow Pine Mine (sample site Y -9, Fig. 4). Tertiary dikes ranging in composition from rhyolite to diabase are present within the district, and extrusive rocks of the Tertiary Thunder Mountain cauldron complex are exposed east of the district (Fig. 4). The rhyolite and quartz latite Tertiary dikes are light colored and have a very fine grained groundmass. Latite (called lamprophyre) and diabase dikes are younger than the more felsic dikes (Cooper, 1951 ), and they contain biotite and plagioclase phenocrysts, respectively. Opaque minerals are common in the mafic dikes. Extrusive Tertiary rocks of the Thunder Mountain cauldron complex, just east of the Yellow Pine district, were first recognized by B. F. Leonard iCater and others, 1973; and Leonard and Marvin, 1982 1 1984 ). Regional Structure On the western side of the Challis quadrangle (Fig. 3), the dominant structural pattern is formed by north -south to N. 300 E.- trending faults that are regional in extent and can be traced for more than one degree latitude. The faults are upthrown on the west (Kiiisgaard and Lewis, 1985) and have a right - lateral component because the major stress was directed from the southwest. East of the north - trending fault set is another set of major faults trending N. 300-60° E. (Fig. 3, the trans - Challis fault system), possibly resulting from earlier stress directed from the northwest. Stratigraphic markers along the faults are rare because the faults are in plutonic rocks. Kiilsgaard and Lewis (1985) developed a general stratigraphy in the batholith and determined that the western side of the Deadwood fault zone was upthrown several kilometers relative to the east side. Right - lateral movement is known from the secondary fracture patterns. Where the main faults splay to the east (Fig. 5), the fault intersection has an extentional, open -space component, which is important because these intersections localize the mineral deposits. The two north - trending faults important in this discussion of alteration and mineral deposits are the Deadwood -South Fork Salmon fault and the Meadow Creek fault zone (Fig. 3). The latter is host to the W- Au -Ag -Sb mineral deposits of the Yellow Pine Mine. The West End Mine is located along a northeast- trending splay related to the Meadowcreek fault system in which the Seeing Eye fault (Leonard, 1973b) is a north - trending shear set. The granodiorite of the Idaho Batholith was strongly brecciated along the faults within a zone as much as 1 -1.5 km wide (Leonard, 1983). Circulating fluids caused major textural and chemical changes in these brecciated areas. The length of the faults and width of alteration along them suggest that the faults extend deep into the crust, providing conduits for continued circulation of heated fluids. The presence of paleo -hot springs and a few active hot springs along the regional faults also suggest that the faults are deep- seated. Cross - cutting relationships of scheelite- quartz and quartz -only veins at the Yellow Pine Mine and the Golden Gate Mine shows several stages of fault movement. The evidence suggests that silica deposited from the fluids moving along the faults locally plugged the fractures until subsequent fault movement broke the seal and fluid flow continued until the area became clogged again. Alteration Along the north- to northeast - trending shear zones, the original medium- to coarse - grained biotite granodiorite and porphyritic granodiorite of the batholith (Fig. 6) have been 583 440 52' 30., COOKRO, SILBERMAN, BERGER 115 °20' 0 1 KILOMETER Figure 4. General geology and sample locations —the Yellow Pine mining district from B. F. Leonard (written comm., 1985) and D. E. White (1945). Base map: Stibnite, Idaho 7'h minute quadrangle. See Fig. 2 for rock descriptions. The dashed line is the Meadow Creek fault and the numbers are sample locations. strongly argillized, silicified, and sericitized. Fine - grained clay and secondary silica permeate the altered batholith, giving the altered granitic rock a much finer grained appearance than when fresh (Fig. C). Megascopically, the mottled medium- to coarse - grained rocks, either black and white, or black, pink and white, become a very homogeneous looking light -tan to brown to gray where altered. The altered granodiorite, because it lacks mafic minerals and is fine grained, is sometimes called alaskite, or aplite, or leucocratic granite in the literature. ijb: , . - -- ,. YELLOW PINE MINING DISTRICT Key to Mine and Sample Locations for the Yellow Pine District Map (See Appendix A for sample descriptions) Location Description 1 Yellow Pine pit, granodiorite - sample Y2 2 Yellow Pine pit, Au zone - Y1 series samples 3 Yellow Pine pit, W and Sb zone - Y3 series and Y4 series samples, and samples M002, MO10, M032, M034, M0113, M0130 4 Background samples - Y7 series samples 5 Background sample - sample Y19 6 West End Main pit - Y8 series samples 7 West End Upper pit - Y5 series samples 8 Background sample - sample Y21A 9 Background sample - sample Y11 10 Background samples - Y12 series samples 11 Background sample - sample Y10 12 Background samples - Y9 series samples 13 Background sample - sample Y13A 14 Background sample - Y18 series samples 15 Hermes mercury mine 16 Background sample - sample Y17 17 Background sample - sample Y15 18 Background samples - Y16 series samples 19 Fern mine (Hg) - Y14 series samples 20 DMEA prospect (also called Sulphide #10) - Y6 series samples 21 Meadow Creek mine (gold, silver and antimony) 22 Bonanza prospect - Y20 series samples Figure 5. Diagram of fault refraction and shattering within the Idaho batholith, and mineralization via infill and replacement (modified from Pollard and Taylor, 1985). 585 COOKRO. SILBERMAN, BERGER Figure 6. Coarse - grained unaltered biotite granodiorite (upper left) of the Idaho Batholith, granodiorite after extreme alteration (lower right) caused by faulting, argillization, silicification, and sericitization. The altered rock is light tan to light grey, fine grained, vuggy, and oxide -rich. Secondary silica, in veins and disseminations, is the most pervasive alteration of the district; it has replaced and permeated the rock within the fault zones, where in places the silica makes up greater than 9017c of the rock. Quartz occurs in stockwork veins and veinlets, as disseminations, in colliform bands, and with reticulate textures. Vugs formed by leaching of feldspar grains or formed in extensional fractures are either partially filled with euhedral quartz ± scheelite ± gold and commonly with Mn and Fe oxides or they are completely filled with secondary quartz, forming a quartz -eye pattern in the rock. Plagioclase is sericitized; fine flakes of sericite are common although they are lacking in some of the mineralized zones. Feldspar grains are commonly argillized in the fault zones. Clays minerals that formed from the alteration of feldspar grains are commonly leached out, and the resulting void is filled with euhedral clear quartz. These altered silicates were no doubt an important source of the secondary silica within the altered plutonic rocks. Dark biotite grains in unaltered granodiorite are only remnant shreds in the altered rocks, or they have been recrystallized to either chlorite + fine mica and opaque minerals ±sphene, -.or epidote ±calcite and opaque minerals. The most common opaque minerals occurring in replaced biotite are arsenopyrite, pyrite and pyrrhotite. Calcite occurs as discreet grains in inetasedimentary inclusions within the batholith, and as crystalline calcite in veins and breccia infillings. The calcite veins and fillings are probably hydrothermal in origin. The hydrothermal ( %) calcite is sometimes dark in color and contains Mn and Fe oxides and abundant opaque minerals, which include fine grains of arsenopyrite and pyrite. This type of calcite is preferable to the calcite within metamorphic rocks for replacement by scheelite; it was more massively replaced and resulted in very high grade tungsten ore. 586 YELLOW PINE MINING DISTRICT Occurrence of Gold Submicron -sized gold occurs within sulfides (pyrite, arsenopyrite and stibnite) and as free gold. The more favorable ground for mining is in the oxidized zones, like that of the West End Mine, versus the less amenable ground of the sulfide -rich Yellow Pine Mine. There is some evidence for several phases of gold mineralization in the district. Arsenopyrite and pyrite, presumably deposited in an early phase, are disseminated within slightly altered granodiorite and may contain gold. Cooper (unpub. data, 1949) describes some of the gold ore in the Yellow Pine pit as being in "comparatively little altered quartz monzonite." This siightly altered granodiorite was both Na- and K- metasomatized, and veins of albitic plagioclase and adularia are common. Arsenopyrite and clusters of fine pyrite grains with altered cores are commonly included in plagioclase, less commonly in adularia veins and along fractures in K- feldspar grains within the gold zones. The sample with the highest gold content is from the gold zone of the Yellow Pine Mine and came from a quartz vein that cuts sericitized and mineralized granitic rock. The vein contains abundant very fine - grained pyrite, arsenopyrite and other indistinguishable sulfides. Within the ore zones, biotite is often replaced by arsenopyrite, pyrite and pyrrhotite, and calcite veins contain arsenopyrite and pyrite grains. Whether the gold was deposited in early and late phases or was continuously being deposited is currently unknown. Within and in the vicinity of the Yellow Pine Mine, gold occurs as native gold (White, 1940), in the minerals arsenopyrite and pyrite, and in the zones of the pit having high concentrations of stibnite and tungsten. (Cooper, 1951). Cooper (unpub. data, 1949) reports arsenopyrite having a consistent ratio of 0.05 oz. gold to 1 percent arsenic in the Yellow Pine Mine. Chemical data also suggest a strong correlation of gold with arsenic. There is also evidence of a gold association with antimony in the stibnite zone of the Yellow Pine pit (Cooper, 1951). It has not been determined how the gold occurs with or within the stibnite, but it is with this sulfide and not just with disseminated arsenopyrite in the stibnite zone. At the West End Mine, mineable concentrations of gold occur within fractured, oxidized metasedimentary rocks of a roof pendant within the batholith. Geochemical anomalies reported by Cooper (1951) and later followed up by a soil sampling program by Leonard (1973b) led to exploration and development of the mine by Superior Mining Company. The property was recently acquired by Pioneer Metals. Although quartzite and mica schist are the most favorable host rocks, all lithologies sampled in the upper and lower pits contain anomalous concentrations of gold. Submicron -sized native gold, which occurs along fractures and disseminated, throughout the strongly oxidized and fractured rock, makes up the ore (Lasmanis, 1981). Lasmanis (1981) described the protore as auriferous arsenopyrite, which is present at lower elevations in the Yellow Pine pit. Auriferous arsenopyrite is not observed in the mine workings or, thus far, by ore microscopy from samples collected at the Yellow Pine or West End Mines. Dikes of porphyritic dacite or latite are present in the mine area and contain stockwork quartz - sulfide veins; the dikes are also within the ore bodies (Lasmanis, 1981). Occurrence of Tungsten Scheelite occurs as (1) fine to coarse crystals replacing calcite (Figs. 7a and 7b), (2) solid inclusions in quartz veins (Fig. 7a and 7b), (3) fine coatings on rock fracture surfaces, mixed with fine - grained quartz, and (4) clay -sized euhedral to subhedral crystals on manganese oxides. Type 1 crystals occur within the W ore zone of the Yellow Pine pit where tungsten - bearing quartz veins are in contact with calcite. The calcite is either hydrothermal calcite filling in the matrix of breccias, or in metasedimentary breccia clasts. Altered granitic rocks having high tungsten content have been strongly fractured and the quartz - scheelite veins fill 587 COOKRO, SILBERh1AN. BERGER these fractures. The high -grade tungsten zone of the Yellow Pine pit contained coarse scheelite crystals replacing hydrothermal calcite cut by quartz feeder veins. Coarse scheelite crystals occurring in calcite- bearing metasedimentary inclusions are scattered around the margins of the inclusions and near quartz veins, but the scheelite replacing the hydrothermal calcite results in extremely high grade scheelite ore. Type 2 crystals occur in rungs ten -bearing zones in the Yellow Pine pit, the West End Mine and the DMEA property (also called Sulfide #10) and are common throughout the district. Some tungsten- bearing quartz veins contain mostly clear quartz, but the quartz containing arsenopyrite or stibnite has a gray color. The tungsten- bearing quartz veins and tungsten- bearing calcite and calcite veins are interwoven. Where the rungs ten -bearing quartz Figure 7a and b. Tungsten ore from the Fellow Pine Mine. Scheelite within quartz veins (solid inclusions) and replacing calcite (the nearly pure white areas in photo b) in the breccia matrix. a: in ordinary light, b: in ultraviolet light showing fluorescing scheelite. 588 rt� YELLOW PINE MINING DISTRICT veins contact the hydrothermal calcite, calcite is massively replaced by scheelite; where calcite veins and quartz veins are in contact with each other, scheelite crystals often develop within the calcite veins with their c -axis parallel to the contact. Type 3 scheelite crystals, which are common in the district, occur on fracture surfaces. These very fine - grained crystals occur with quartz as films on open rock fractures; they are rarely present on fracture surfaces in Tertiary dikes. Type 3 crystals occur within layers of colliform bands between quartz layers. It is possible such scheelite is being deposited at present, as it fills slight surface depressions in rock joints that host a nearby active hot spring. The water in this hot spring on Hot Creek has anomalous (6 ppm) tungsten concentrations (B. F. Leonard, oral comm., 1982). Type 4 scheelite crystals occur on a punky mixture of Mn and Fe oxides and cryptocrysta I line quartz. This mixture resulted from dissolution of Mn- and Fe- bearing remobilized calcite, probably by acid fluids. Clay -sized euhedral to subhedral crystals of scheelite cling loosely to the manganese oxides (Cookro, unpub. data, 1987; Petersen, 1984). In hand specimens, a slight dusting of tiny scheelite crystals occurs on the oxides. Although it has been previously noted that the Tertiary dikes are associated with the tungsten ore bodies (Cooper, 1951), tungsten content actually drops off in the vicinity of the dikes. In one place, however, scheelite was observed to extend into a fracture within a dike of Tertiary age. The scheelite at the New Snowbird Mine (Fig. 2) was in a tiny 1 -3 mm fracture that crossed into the dike which demonstrates that scheelite deposition continued after the emplacement of the Tertiary dikes. Scheelite occurs around altered breccia fragments of granodiorite to which quartz has been added and in which the mafic minerals are mostly replaced. In places the breccia fragments are hardly visible in hand specimen unless an ultraviolet light highlights blue -white fluorescing scheelite. The scheelite occurs in quartz veins and calcite veins in several superimposed stages of brecciation and tungsten mineralization. Isotopic Relationships Regional light stable isotopes and K -Ar ages Light stable isotope (oxygen and hydrogen) measurements of samples from the Atlanta lobe region of the Idaho Batholith by Criss and Taylor (1983) demonstrated that meteoric - water- dominated hydrorhermal systems of regional extent were centered upon and generated by Eocene intrusions (37 -46 ma) and caused significant isotopic exchange in silicate minerals of the Cretaceous granitic rocks. 160/160 was strongly lowered in feldspar and biotite and slightly lowered in some quartz (quartz is more refractory to oxygen isotope exchange than other silicates). D/H was strongly lowered in biotite and slightly lowered in muscovite. Regional K -Ar data of Criss and others (1982) shows a good correlation between reset biotite K -Ar ages (due to argon loss) and areas of depletion of 180 and D. They also illustrate that a strong correlation exists between the occurrence of Au -Ag mines and prospects and the boundary zones of the meteoric - hydrothermal systems. This implies that many of the deposits were formed during the Eocene (Criss and Taylor, 1983, p. 659). The occurrence of Au -Ag deposits in volcanic rocks of Eocene age, such as at Yankee Fork, Thunder Mountain, and elsewhere in the region (Hardyman, 1985; Criss and Taylor, 1983, McIntyre and Johnson, 1985; Manghan, 1984) corroborates this implication. The Yellow Pine district fits this pattern as it occurs along one of the boundary zones of a large meteoric - hydrothermal system (Criss and Taylor, 1983). However, recently published 40Ar /39Ar spectrum ages of sericite and adularia from several Au -Ag districts in the batholith and from metamorphosed roof pendants (Lund and others, 1986; Snee and others, 1985; Gammons and others, 1985) are Late Cretaceous and correspond to late -stage intrusive activity of that age in the batholith. 589 i COOKRO, SILBERMAN, BERGER K -Ar ages at Yellow Pine A single 40Ar /39Ar spectrum age determination of sericite from a sample collected at the Yellow Pine Mine (L. W. Snee, written comm., 1986) is also Late Cretaceous. However, three conventional K -Ar age determinations from replacement adularia collected from the Au ore zone yielded an average age of 57 ±1 ma (Lewis, 1984), which is older than the Eocene event but much younger than the Cretaceous alteration age. K- feldspars are more susceptible to argon loss, measured by conventional K -Ar techniques, than muscovite during post crystallization thermal events (Dalrymple and Lanphere, 1969; Evernden and Kistler, 1970; Hart, 1964; Harrison and others, 1979). We suggest that the feldspar ages could represent partial argon loss from an original Late Cretaceous crystallization event. Similar relationships of sericite and K- feldspar (where the K- feldspar was reset by subsequent events) is demonstrated at the Getchell disseminated, sediment - hosted gold deposits in Nevada (Silberman and others, 1974). Criss and others (1982) show a diagram contouring apparent K -Ar biotite ages in the region, which were reset during the Eocene meteoric - hydrothermal event. The 60 ma contour passes close to Yellow Pine; thus, it appears likely that Yellow Pine was thermally affected by that event. Additional K -Ar analyses, particularly 40Ar /i9Ar spectrum measurements on a variety of original and alteration minerals at Yellow Pine are necessary to clearly establish the thermal history. Y-5(1) West End Mine -upper pit granitic dike, sericitic Quartz (vein) +12.3 -1002 alteration, stockwork quartz veining Muscovite (primary) + 8.3 -83 Y -84 West End Mine -lower pit Quartz (host rock) +13.8 -942 brecciated, oxidized Quartz (vein) +13.9 -1112 quart-zite ore, stockwork Muscovite (detrital) +10.4 -84 quartz veining Y -18 Roof pendant in batholith Quartz +12.4 -114= pyritic, micaceous quartzite ' Relative to SMOW z From crushed fluid inclusions 590 Table 1 Stable isotope data from the Yellow Pine Mining District, Valley County, Idaho Sample Setting Mineral d1800 /00' dD1800 /00' Y -1 Yellow Pine Mine Quartz (host rock) +12.4 -1042 Au zone, sericitic Quartz (vein) +16.8 -1002 alteration — stockwork Sericite +12.0 -84 quartz - veined granitic rock Y -3A Yellow Pine Mine Quartz (host rock) 9.8 -842 Sb zone, sericitic Sericite + 9.0 -79 alteration, silicification Y-5(1) West End Mine -upper pit granitic dike, sericitic Quartz (vein) +12.3 -1002 alteration, stockwork quartz veining Muscovite (primary) + 8.3 -83 Y -84 West End Mine -lower pit Quartz (host rock) +13.8 -942 brecciated, oxidized Quartz (vein) +13.9 -1112 quart-zite ore, stockwork Muscovite (detrital) +10.4 -84 quartz veining Y -18 Roof pendant in batholith Quartz +12.4 -114= pyritic, micaceous quartzite ' Relative to SMOW z From crushed fluid inclusions 590 YELLOW PINE MINING DISTRICT Light Stable Isotopes at Yellow Pine A reconnaissance survey of oxygen and hydrogen isotopic ratios in quartz, quartz veins, and sericite was made in the district. Samples included a variety of mineralized rocks from the Yellow Pine and West End Mines and a sample of unaltered quartzite from near the Fern Mine. The isotope results are summarized in Table 1. A summary of oxygen and hydrogen isotope data from the Atlanta lobe region of the Idaho batholith (Criss and Taylor, 1983) and of other relevant rocks and minerals is included in Table 2. Oxygen Isotopes The oxygen isotope composition of host -rock quartz from altered granitic rocks, containing younger quartz veins, at Yellow Pine is not distinguishable from that of fresh granitic rock of the Idaho batholith. The 5180 values of quartz from mineralized quartzite at the West End Mine and from unmineralized quartzite near the Fern Mine are both slightly higher than that of typical quartzite of eastern Nevada (no background data are present from the Idaho batholith region outside the Yellow Pine district) but is within the range of quartzite in general (Lee and others, 1985; Epstein and Taylor, 1968). Quartz is more refractory to oxygen isotopic exchange than other silicates (Criss and Taylor, 1983; Taylor, 1968). Background data do not exist for oxygen isotope compositions of igneous muscovite in this region. 5t80 values for sericite and muscovite from altered igneous rocks at Yellow Pine are similar to values for unaltered igneous rocks from the Basin and Range province and for sericite formed by deuteric processes in the Basin and Range rocks (Lee and others, 1984; Tables 1, 2). The host -rock quartz, muscovite, and sericite at Yellow Pine do not appear to have undergone isotopic exchange with a heated, dominantly meteoric water (46150 depleted). In contrast to the minerals at Yellow Pine, sericite and quartz formed by alteration at Butte, Mont., from the action of heated, dominantly meteoric water are variable, but have many strongly 180 depleted values; the sericite shows extreme D depletion. Most of the Yellow Pine district was mineralized at much lower temperatures than the Butte district (T. M. Cookro, unpub. data, 1987; Cookro and Silberman, 1987) and, therefore, comparatively less isotopic exchange would be expected. Quartz from stockwork veins at the Yellow Pine and West End Mines appear to be slightly enriched in 110 relative to unaltered rocks in the region (Tables 1 and 2). Criss and Taylor (1983) noted a large range of S 180 in quartz veins hosted in granitic rocks of the Idaho batholith. They indicated that high 51110 characterized veins near Au -Ag mines. Oxygen isotope ratios from Yellow Pine are typical of those found in metavolcanic and metasedimentary rocks such as those found along the Mother Lode belt of California, and in southern Alaska gold vein deposits (Table 2). On the basis of the similarity of oxygen isotope composition of veins at Yellow Pine to those listed in Tai le 2, fluids that deposited them appear to have the oxygen isotope characteristics of metamorphic or igneous origin, or at least they have undergone extensive high - temperature exchange with metamorphic rocks (Kerrich and Fryer, 1979; Bohlke and Kistler, 198T)). This is inconsistent with petrographic, textural and fluid- inclusion evidence which was presented by Cookro and Silberman (1987). The difficulty in separating the metamorphic or igneous quartz of the district from the overprinted late, shallow environment quartz may cause this apparent inconsistency. Hydrogen Isotopes The 46D values of sericite and muscovite from altered granitic rocks and quartzite ore from the Yellow Pine district are tightly clustered in the range of -79 to -84 permil. This is abour 20 -30 permil lighter than 5D of muscovite from unaltered granitic rocks in the rest of 591 COOKRO, SILBERMAN, BERGER Table 2 Summary of isopotic results on rocks and minerals from Yellow Pine Mining District, southern part of the Idaho Batholith, and related rocktypes. ( - -) indicate no data. Mineral Setting d180 D Reference Quartz Unaltered granitic +9 to +12 -- Criss & Taylor rocks, Idaho batholith (10.2 + 1,3) (1984) Quartz Quartz veins in -6.2 to +14.6 -- batholith K- Feldspar Quartz veins in 8.2 to +10.6 -- Criss (1980) batholith Muscovite Quartz veins in -- -50 to -60 Criss & Taylor batholith (1983) Muscovite Plutonic rocks 8.2 to 11.0 -60 to -70 Lee & others eastern Nevada, (1984) southern Basin & Range Sericire Deuteric alteration of 9.6'to 11.1 -67 to -86 " feldspars, in above Quartz Yellow Pine Mine, 7.1 to 10.1 -- Lewis (1984) K- feldspar alteration Gold zone Quartz Fern Mine, hypothermal 11 to 15 -- Lewis (1984) Adularia Yellow Pine Mine, K -feld- 5.2 to 7.7 -- Lewis (1984) spar alt., gold zone Sericite Yellow Pine Mine, K -feld- 5.4 to 11.6 -- Lewis (1984) spar alt., gold zone Granitic Unaltered, Yellow Pine 6.9 to 9.4 -- Lewis (1984) rock Mining District Granitic Altered, K- feldspar, rock early gold phase 8.0 to 9.9 -- Lewis (1984) Quartz Quartzites, eastern Nev. 10.2 to 11.8 -- Lee & others (1984) Muscovite Quartzites, eastern Nev. 7.5 to 10.5 -60 to -81 Lee & others (in press) Quartz Veins & replacement +15.9 to +21.7 -- Bohlke & quartz in altered rock— Kistler (1986) Mother Lode, Calif. Quartz Veins in Dome Mine +14 to +15 -- Kerrich & Porcupine Dist., Canada Fryer (1979) Quartz Metasedimentary & granite +13 to +18 -- Mitchell & hosted, southern Alaska others, (1981); M.L. Silber- man, unpub. data, 1985 592 YELLOWY' PINE MINING DISTRICT the Idaho Batholith (Criss and Taylor, 1983; Table 2). The Yellow Pine SD ranges overlap those of sericite formed by deuteric alteration of feldspar in granitic rocks of eastern Nevada, which themselves have SD values 10 -20 permil lighter (depleted in D) than those of unaltered rocks (Lee and others, 1984; Table 2). The D/H data suggest some isotopic exchange between the sericite at Yellow Pine and heated D- depleted fluid, such as meteoric water. Eocene meteoric water in this region had isotopic compositions of approximately -110 SD and -15 permil ,3180 (Criss and Taylor, 1983). Isotopic equilibration between the muscovite and sericite at Yellow Pine and a fluid of this composition must not have been complete, otherwise the muscovite and sericite SD would have been considerably lower at any probable temperature of interaction (see Table 2 of Criss and Taylor, 1983), as would their 6"0 values. The presence of a strongly D depleted fluid at Yellow Pine is also indicated by low SD values of fluids released by crushing and vacuum extraction of fluid inclusions from quartz from veins and host rocks (Table 1). The vein quartz in particular has consistently low SD, -100 to -111, which is identical to the value calculated for Eocene meteoric water by Criss and Taylor (1983). &D values of quartz from host rocks, on the other hand, vary widely. The higher SD values overlap those characteristic of magmatic or metamorphic fluids (Taylor, 1974) and may indicate the crystallization of quartz in its original environment. We consider it probable that heated Eocene -age fluids of meteoric origin circulated at Yellow Pine, as the reset K -Ar feldspar ages (Lewis, 1984) suggest, and as the correspondence of fluid SD values with those that would be expected for Eocene water in the vein quartz corroborates. Temperatures of mineral deposition, for the most part, were low (less than 200° C) as suggested by the epithermal and textural characteristics of the late quartz, by fluid inclusions, by the lack of oxygen isotopic equilibration between fluids of this composition and the quartz, sericite and muscovite, and by the suggested partial hydrogen isotopic exchange of the sericite. Petrographic and fluid - inclusion surveys suggest a deep plutonic or metamorphic environment for only some of the sphalerite, a trace mineral in the district. The other sulfides and scheelite were deposited in an epithermal environment, and fractures were the major deposition control. The deposition of Au (only observed as native Au in one sample from the district) appears to have been dependent upon a wide range of conditions. At least part of the deposition of metal- bearing minerals appears to have been a meteoric water - dominant event during the Eocene. Preliminary Fluid Inclusion Data 1 Inclusions from fluids that circulated in deep plutonic or metamorphic environments and from fluids of shallow environments are both present in the district. Deciphering the complex history of the Yellow Pine district requires more detailed fluid inclusion work, but a preliminary survey reveals some characteristics of the quartz within the district characteristic of the two environments. The deep- environment quartz is characterized by (1) ubiquitous, wispy textures of secondary inclusions defining millions of healed microfractures which cause the quartz to be cloudy or milky in appearance, (2) the presence of several one phase aqueous inclusions, concentrations of inclusions with inconsistent liquid to vapor volumetric ratios at grain boundaries, (3) the presence of healed microfractures with inclusions oriented perpendicular to planes, and (4) the presence of gases (CO, ?,CH2 ?, and N,,?) under pressure within many inclusions. Sphalerite is sparse in quartz from a deep environment. Quartz veins containing inclusions typical of a shallow depositional environment cross- cut the milky quartz veins. The shallow quartz characteristically has cockscomb, cryptocrystalline, or chalcedonic texture. Inclusions in cryptocrystalline and chalcedonic quartz are characteristically smaller than 2 mm while those in open- space - filling quartz are 593 COOKRO. SILBERMAN. BERGER characteristically liquid -rich, two- phase, primary aqueous inclusions. The shallow quartz is the dominant variety of quartz deposited during mineralization. The cryptocrystalline and chalcedonic quartz in some samples from the Yellow Pine Mine have inclusions that are too small to study; this is common with quartz thought to have formed at temperatures less than 2001 C. Scheelite, stibnite, and arsenopyrite are included within the shallow quartz. A third type of quartz is clear and is always formed around the margins of the deep quartz. The deep quartz, where surrounded by clear quartz, is rounded, suggesting that clear quartz formed at the expense of deep quartz. Epithermal quartz cuts across and grades into the margins of the clear quartz, which is also considered to be of shallow origin. Scheelite is also-present within the clear quartz. A possible mechanism for the formation of the cleat quartz could have been the local buildup of pressure in areas along faults that were completely sealed with silica and formed a closed system. The margins of the primary quartz would . recrystallize when the pressure was released by fault movement (Fournier, 1986). The results of our quartz petrographic and fluid - inclusion survey suggest that Au deposition occurred over a wide range of conditions. The stibnite and Scheelite depositional event was more constrained in regional extent than the gold depositional event. These minerals are concentrated in zones of open brecciation, and fluid- inclusion morphology suggests a low temperature (< 200° C) environment for both of these minerals. Geochemistry A total of 64 rock samples were analyzed from 21 different mines, prospects, and nonmineralized background locations within the Yellow Pine mining district. Sample locations and descriptions are shown on Figure 4. Sample preparation and analytical procedures Samples weighing 2 -10 kg were collected and crushed with a mechanical jaw crusher and then pulverized to less than 200 mesh ("0.15 mm) before splitting for analyses. Analyses consisted of semiquantitative emission D.C. arc spectrography (E -spec) for 31 elements using a method described by Grimes and Maranzino (1968). Table 3 lists the limits of determination for those elements. Wet chemical analyses supplemented the E -spec results for certain elements in which the determination limits were too high or for elements that were not determinable by E -spec. Elements analyzed by the wet methods included Au, As, Sb, Hg, Zn, T1, Te, and F. A summary of the methods used and their limits of determination and their relative standard deviations are listed in Table 4. Analytical results are tabulated in Appendix B and, for selected elements, are shown as bar graphs in Figures 9 -16. Distribution of trace elements at Yellow Pine Cooper (1951) and Lasmanis (1981) both suggest that ore deposits in the Yellow Pine district are zoned according to depth at the time of mineralization. Lasmanis (1981) tabulated the present elevations and the principal metals produced from mines and prospects. Hg deposits and concentrations (Fig. 8a) occur at high elevations, Au at intermediate elevations, (Fig. 9b) and Ag -Sb -W at the lowest elevations. Analytical results are tabulated with elevations of the samples in Appendix B and arranged in bar graphs in order of elevation (Figs. 9 -16). Patterns on the bar graphs represent different lithologies. The key to the patterns is on Fig. 9. Because the sample suite at each location was too small for meaningful statistical analysis and quite a variety of lithologies are represented at each location, we have summarized the results element by element, as follows. 594 YELLOW PINE MINING DISTRICT Gold Of all the mines and prospects sampled, the highest gold content (30 ppm, Fig. 10) was found in a quartz vein cutting silicified and sericitically altered granitic rock in the Au zone of the eastern part of the Yellow Pine pit. Gold content is highest in this zone, although both the Sb and W zones also have high Au contents (0.5 -3.3 ppm). Distribution of Au in our samples from the West End Mine was erratic. Samples from the lower (main) pit at 2073 m (6,800 ft) generally contain between 0.3 and 1.7 ppm Au in oxidized schist and quartzite ore, Table 3 Limits of determination for the spectrographic analysis of rock based on a 10 mg. sample Element Lower Determination Limit Upper Determination Limit Percent Iron (Fe) 0.05 20 Magnesium (Mg) 0.02 10 Calcium (Ca) 0.05 20 Titanium (Ti) 0.002 1 10,000 Parts per million Manganese (Mn) 10 5,000 Silver (Ag) 0.5 5,000 Arsenic (As) 200 10,000 Gold (Au) 10 500 Boron (B) 10 2,000 Barium (Ba) 20 5,000 Beryllium (Be) 1 1,000 Bismuth (Bi) 10 1,000 Cadmium (Cd) 20 500 Cobalt (Co) 5 2,000 Chromium (Cr) 10 5,000 Copper (Cu) ' 5 20,000 Lanthanum (La) 20 1,000 Molybdenum (Mo) 5 2,000 Niobium (Nb) 20 2,000 Nickel (Ni) 5 5,000 Lead (Pb) 10 20,000 Antimony (Sb) 100 10,000 Scandium (Sc) 5 100 Tin (Sn) , 10 1,000 Strontium �(Sr) 100 5,000 Vanadium (V) 10 10,000 Tungsten (W) 50 10,000 Yttrium (Y) 10 2,000 Zinc (Zn) 200 10,000 Zirconium (Zr) 10 1,000 Thorium (Th) 100 2,000 595 COOKRO. SILBERMAN. BERGER although one sample from a clay seam contained a high value of 6 ppm. Samples from the upper pit at 2170 m (7,120 fry generally had lower Au content, only 0.1 -0.3 ppm. Samples from the Fern Mine, at 2438 m (8,000 ft) had low Au values, in the range of 0.1 ppm or less, except one sample of argillic gouge which contained 1.5 ppm Au, collected beneath a jasperoid outcrop. A sample from the DMEA prospect at 2024 m (6,640 ft) contained 1.6 ppm Au and most of the gold - related metals. Au concentration (Fig. 9b) generally decreases with increasing elevation in the Au zone of -.he Yellow Pine pit. It is still quite high in the W and Sb zones of the mine. Cooper (195 1) stated that gold concentration was relatively low in the Sb and W ore bodies, which was true from an economic standpoint at that time, but the Au contents of the whole Yellow Pine Mine system are strongly anomalous. Background Au contents in most samples of nonmineralized rocks were below 0.05 ppm, the lower limit of determination. Exceptions include a sample of fault gouge from near the West End Mine which contained 1.3 ppm Au, and some samples collected along the access Table 4 Chemical methods used AA = atomic absorption; Inst. = instrumental; SI = specific ion; S = spectrophotometry. Element Method Determination limit (micrograms /gram or ppm) % RSD Reference Gold (Au) AA 0.05 9.3 -42.5 O'Leary and Meier Mercury (Hg) Inst. 0.02 8.2 -30.4 Modifications of McNerney and others (1972) and Vaughn and McCarthy (1964). Antimony (Sb) AA 2 1.1 -10.0 Modifications of Viets (1978). Arsenic (As) AA 5 1.6 - 6.4 do. Zinc (Zn) AA 5 0.9- 3.4 do. Thallium (TI) AA 0? 2.4 -14.4 Hubert and Lakin (1973). Fluorine (F) SI 100 .98- 5.51 Hopkins (1977) Tellurium (Te) AA 0.005 2.8 -15.6 Chao and others (1978). RSD = Relative Standard Deviation Emmissions spec. by M. S. Erickson and E. F. Cooley Wet chernistry under the direction of R. M. O'Leary 596 YELLOWY% PINE MINING DISTRICT y` -101 it 4414 k le Ar K , JO s s ti �► . Ar Of OPA Figure 8a and b. Scheelite in altered granitic rock of the Idaho Batholith showing several stages of brecciation and quartz + scheelite veining. Sample is from the Golden Gate Mine. a: altered granitic rock in ordinary light, bar is 1 cm., a: sample in ultraviolet light showing fluorescing scheelite. road, also near the West End Mine, which contained 0.05 to 0.15 ppm (020 in silicified limestone from above the West End Mine). All other samples from along the access road had Au contents that were detectable but below the loner limit of detection. Elsewhere, Au content of samples was generally not detectable. To better interpret the background distribution of Au, lower determination limits would be necessary. Background, nonmineralized samples from high elevations near the Fern Mine did not contain detectable Au, with the single exception of a Fe -oxide pod in limestone; the gold content of this sample was probably related to the previous sulfide content of the pod. The nonmineralized granite 597 Hg AA 0.01 LD L---f-f 2438 M j 2170 M 0.1 M11 I ) FERN MINE 2073 M� (6800') WEST END PIT (MAIN) 2024 M 00 1902 18•0 M ff 3 w =V= 1890 M ZONE) 10 U �0�0 YA PPM W E SPEC 10 LD 100 L 1000 10,000 'U'jo 2438�(8�000') FERN M�INE � N ZA (N D)) 10 0 El • El Fa E3 ku4VU-1 YELLOW PINE PIT (Sb ZONE) (ND) M mom KEY To BAR GRAPtj PATTERNS .. . ... ... . .. 1890 M (6200') YELLOW PINE PIT (Sb ZONE) ..... r,' 13 EM EM EM Granite clay goilge EMSchist/Quartzite Skarn Jasperoid/Carbonate Quartz vein Tertiary dike Figure 9a and b. liar graphs showing (a) Hg and (b) W contents at selected sample locations. AA� atomic absorption, E sPec= emissions spec-, 1-1)= limit ND� [lot detected. 11 of detecti(i O O O Pj As ESPEC LD 10 100 2438 M (80tOO�')F ERN MINNE L 2170 M (7120') WEST END PIT (UPPER) 2073 M (6800) WEST END PIT PPM 1000 10,000 J1L1._1 1 1 1 1 1 1 1 I I I I I I I l i 1 • . / 1 Nr }YiA:�!. YAM.• �tY�l iV�i!G!•�iC�f�rli!.1.�.�.A.�.r� .. . n •.•nyr � ...tl. •. •y !� r�•py � 1 1 .. R... aA-!• A!•. l: f.. iY'•.• 1!• 1Y1!•! ITi!•i!�aT•!!•y�.'I.T.•RI:f•)!1 '1 11 _YE LOW • l ��•,rrrJ:r��';f. {/r�j',••'�' 1�,j .•�v'r.r {r r¢f•rvr•.r...vr. rr r...,.•. yv• .yv .y .•••• J�• 1L�d. 5'.•:•N.i:��•:rdT:r•JY7l:{•��1! :S;i ,iiJ:S ••il� %If•��•�J�••� .�.��� • �r••J •••' }r i. i•�•/.� ''1 M (6200 :C I -. -_... ••.•••.... c •�a-err4i }•..bTft• }•�SY.�i!�ir� • 1 / • Au AA 0.01 LD 0.1 1.0 —L J_LI I II I I I I I I I I I I I III 10 2438 M (8000) FERN MINE 2170 M (7120') WEST END PIT (UPPER) 2073 M (6800'1 WEST END PIT (LOWER) 13 M h O b 2024 M (6640')DMEA 7 1902 M ;(6200') ONANZA z z' 1890 M LLOW PINE PIT (Au ZONE) b ® ® ® - - 00 1890 M LLOW PINE PIT (W ZONE) y •vv •5 •.• rrr.•.v..wnv r- r- rorevw.•.•..,• • • Figure Ma and h. Bar graphs showing (a) As — r Patterns are explained in Fig and (b) Au contents at selected sample locations. E spec = emissions spec., AA= atomic absorption; LD= limit of detection. COOKRO, SILBERMAN, BERGER sample taken at the entrance to the Yellow Pine pit did have 0.1 ppm Au, but the analysis was not reproducible. On the basis of the current sample suite, no intrinsic pre - concentration of Au appears to exist in rocks of the region, although barely detectable to low -level concentrations are p resent in several lithologies along the access road near the West End Mine (particularly in quartzite and schist, which are the most favorable host lithologies, and in amphibolite and felsic dikes). Although we do not have background ( nonmineralized) samples from around the Yellow Pine Mine, we suggest the low -level concentrations may be a primary halo around the West End .Mine rather than a regional elevation in Au background levels. Tungsten _ Tungsten analyses (Fig. 9b) in this study were done by E -spec, which has a limit of determination of 50 ppm; therefore, determining the distribution of low -level W in the samples was not possible. Cooper (1951) indicates that W mineralization followed Au mineralization, and Lewis (1984) agrees. The present study indicates that W was deposited during several stages in the regional paragenesis, in a variety of environments, possibly including trace scheelite deposited by currently active thermal springs (see earlier discussion). Significant concentrations of W were found in samples from only three areas: (1) in altered, brecciated granitic rock from the W zone of the Yellow Pine Mine, where concentrations greater than 10,000 ppm 0 %) were detected; (2) in altered, brecciated granitic rock from the DMEA prospect, where 1,000 ppm W were detected; and (3) in jasperoids and manganese- and iron -oxide fault gouge from the Fern Mine, where concentrations in the range 200 -1,000 ppm were detected. Tungsten was not detected (absent at 50 ppm or above) in any of the nonmineralized background samples including talc- silicates, with the exception of a sample of iron -oxide fault gouge from along the access road near the West End Mine, which contained 100 ppm. Antimony Antimony content (Fig. l la) is highest within the Sb and W zones of the Yellow Pine Mine, from which most samples contained 10,000 ppm (170. It is considerably lower, but still anomalous, in the Au zone (up to 100 ppm). The brecciated granite at the Bonanza prospect has 10,000 ppm Sb. The distribution of Sb in samples collected elsewhere in the district does not show any correlation with elevation. Moderate values (>100 ppm) are encountered at the DMEA prospect and occur erratically at the West End Mine, but Sb contents in most samples from those two localities are below 200 ppm. Antimony contents of the Au zone of the Yellow Pine Mine and of the West End Mine are similar. Sb content of jasperoids and iron - oxide fault gouge at the Fern Mine ranges between 50 and >10,000 ppm. The concentration of Sb is highest at the lowest exposed elevations in the Yellow Pine Mine, Sb and W zones and at the hig est elevations at the Fern Mine. However, very high Sb content is not associated with Au mineralization in the samples from either the Yellow Pine or West End deposits. It is interesting to note that the very high Sb content at the Bonanza prospect (10,000 ppm) is not associated with any Au, and at the DMEA prospect, where Au is present, content of As and many other metals are high, whereas Sb content is not. Antimony concentration in non- mineralized, background samples collected throughout the district is strongly elevated relative to crustal average for a variety of lithologies, but no patterns related to elevation are obvious. Samples showing strong oxidation tend to have the highest Sb contents. These samples previously contained sulfcles. Arsenic Arsenic concentration (Fig. 10a) in samples from the Au and Sb zones of the Yellow Pine Mine are consistently high ( >10,000 ppm) but erratic. The W zone also has erratically 600 G1 0 M h h b `z z` c� b n 1 1 1/ 111 / 111 •. • :111 1 1 1 1 /1 111 :111 i BBBB8811BFte�1 I � ®1 1 •:1/ 1 j B� i:'?: }::{Y; :tit ::'3:ti : ;•: ;5'h :Y: � •:11 1 tA! J.:.: r... �Y.: r.•: Jr• �: trr..:.: �iYAYri :r:!JrJ.bY.,Yrd•S:.,Y.Jr.1rrY?I r..rS:.tr..}..v,.:.:s ✓..;r,. >•v r'r :m.,r. {•_ {r .a. {a d{ N.+ Y: r., trA {,•; {•Yi:{{�+:•R��'rrtR{54: {•:i • 1 • 1 �Nr:• J. 1{•.' Jd},', i' i, 1T• ;�;' {Y: {Y : {• } }�Y;rrr.YJJrY.iYdS a. 7AX� }:�'` {v{J • J'! Ong • rJ''r }'; :�:JO:' : ' }:i�::: 'r• }.::: '.. : �'':i':i' r l,�!�� •• J.,•..ti{ • Jy�r,.J,{. r. s•:.{•...•,••. J,..} e,• } ' :•J St • • 1 1 1 • J l• ,•,.;1J,o}J,r.,,,.J••.s;BJ;,¢•! r • ••JJ• r r •••.• rJ i1.. •ir.•.Jl•,•.•,r� 1'JJ• r • • A•• , I • •Jr'• • h .• J J rrr` JrJ•'• }•J• :'�lJ:..•'.as.:f �..• .r.J.. ,.J.,. A. ; N, • {','•'�.Jr:; {Y�l �''�•1•�?:r J, i;:;{ �•:{;{•••{:'•} �' •'•}'l.S.. {•A •Y i9 1.•..e. i71 ,;,;,;, �...,qy ', • r • ..Y ,t �+•J , ��. {i';rr:;1JJ:Y;•:rJ J!rJ rJ'{J•r.,�r✓,,. •�lr{,•. r�,}�',�.r•}JO••JYr•'. {rf }',•,� • � 1 1 ..• eec {•.a�vJ,.,., {•,M,.y,Jle'•:• ¢; '�' ' • ' •,•fl J .�r � ' ��• y:•:• r:• yr{{•: tiR {{. };r,. }. }r,..:'{{.C:aS•k ?:{� +:{•k•:ati • �r�r%,'.Y;;k,Y,�rr'. r ♦�f • /�•,, fhr;,Yr�•.Y�.�,•.,...,. �•• • . r' ,y.�S'' {r�%JJ'.J' r�,•!'��•�'{,:','• Y.f�Jl}'`•'.••'•.,,{J'Jr•, "' •y }'}S ,''1' {�•,;J� N f. l.Fi': N�1frr�l1N.YJ��'•"','Vf rr'jr•�,I {�1•'•, ��;J,,••,,r•'�:" �• ,•; %;'{.', �:;�••,•Yr•,ii;�; �,•:•:r.�Y•:•:�. /I / / / / / // / / /i / / / •'}'•Jr r. • t r; •.o.rrrr Y.i l;; �' ; , 61,••; dSS• x{•}• �?! b: �i{ at: �?: •:•X4v. }r�C{•khs•;t'1:{ {{ {titi?t{ 1{{ {rr}??�}[! • 0 7'7' • • ,�r�::•Y'A�;�;`;,h,;} }rX4j; }Y .... . v / / / / / / / / / / /i / // /i .S �. r ?7i• }:•::: }:•:H; rr �••... KardS• • •.•� i:i' rt Jf 'P;ti�,•y ''y'.�Y •fir • . ',., {OGiS+XdF.{V • fill M h h b `z z` c� b n COOKRO, SILBERMAN BERCER high As but the maximum values are lower than in the o greater than 10,000 Cher two zones. Arsenic content of rock, where it is associated 0 pp also present ata the D anomalous A (but not much Sb). It is generally high (u to 1 S00 prospect in brecciared, altered granitic concentrations of Au and ocher metals The jasperoids and gouge of the Fern Mine contain 1500 to both OOppirs at the West End Mine. indicated a close association of As with Au and indicated that areas with pyrite tended to have good Au grades. This stud ppm As. Cooper (1951) y corroborates the association of Au and with arsenopyrice and pyrite. A11 samples containing 1 Ib and b show that Au has a more consistent association with As than w' g ppm Au have >1w with ppm gs. Figures llb). irh Sb In unmineralized rocks Figs. l0a and average for the lithologies sampled content erratic but commonl determination limit. Arsenic concentrations in excess of 10 y strongly above crustal P occurs in all samples where Au was above of unmineralized lithologies from high elevations near the Fern Mine. I erratic along the access road near the W ppm were detected in all samples of the Yellow Pine Mine is strongly anomalous in As (28 m is distribution is more West End Mine. Altered granitic rock from the margin granite (1.5 -1.9 ppm) Pp m) relative to crustal average for Mercury Mercury content (Fig. 9) does not decrease at lower elevations in the min Mercury content is highest in the jasperoids and gouge of the Fern Mine > is strongly anomalous in samples from most of the rest of the district including mineralized zones. nonmineralized samples. Few samples had less than 0.1 ( 10,000 ppm), but average for the lithologies. Mercury in samples from lower el o strongly most of the ppm, which is strongly above crustal zone of the Yellow Pine Mine and at the Bonanza prospect. In both places, the evations is highest in the W exceed 10 pprn (the upper limit of determination). The Sb and Au zones of th Mine have general] lower highest values y Hg contents but contents of up to 1.8 e fellow Pine from both West End Mine pits are strongly anomalous, containing up present. Samples Samples of the brecciared granite at the DMEA prospect also car In the nonmineralized samples H g P to 4.6 ppm Hg• Hg content tends to be higher n the samples at high elevations, but the distribution is spotty. and a felsic dike, taken along the access road near the Wes End1Mineaarry > n ppm. olice Thallium carry ZO ppm. Thallium concentration (Fig. 12a) is highest (2.4 -43 ppm) at the Fern Mine, but it is at or below crustal average at most of the other mineralized areas. It is most consistently 1-2 ppm, in the Au and Sb zones of the Yellow Pine Mine and generally less than this high, in the W zone. The h- '' concentration in a ppm at the DMEA prospect, where it is barely mineralized above crusstaleaveran at high nice. elevation is 3.4 was not detected (limit 0.2 ppm) in most unmineralized samples, even chose with age for granite. Thallium content. high Hg Silver Silver ( Fig. 1 1 b) favors Lower elevations in the study area, but its distribution irregular. In the Yellow Pine Mine Ag is highest in the W zone (one sample ppm), but high m both the W and Sb zones 1 -st uai is very Silver content is much lower (>0.5-7 ( PPm) and more consistent ino[hetSb zon00 is more common in the lower West End ppm) it than Au n he u High A from the DMEA prospect carried 10 P g g content (up to 200 ppm) Peer pit (up to 3 PPm)• A sample Silver was not detected in samples from the Fern Mine, which is at high PPm g and high concentrations of As, Au, Sb, and Hg. samples from the Bonanza prospect, which is at a lower elevation. g elevation, nor in 602 0 TI AA PPM LD Te AA 0.1 1.0 10 LD Zn E SPEC L1L r r rlrrrlr r r rrr1100 0.01 0.1 LD 2438 M (8000') FERN MINE 1.0 10 1.0 2438 M ) 10 100 1000 (B 10 FERN MINE 2438 M (8000') FERN MINE 2170 M (7120') WEST END PIT (UPPER) "' 2170 M (7120') WEST END PIT (UPPERI 2170 M (71207 WEST END PIT (UPPER) 2073 M (6800') WEST END PIT (MAIN) _- 2073 M (6800') WEST END PIT (MAIN) 2073 M (6800') WEST END PIT (MAIN) N N 2024 M (6640)DMEA - - 2024 M (66407DMEA b 1902 M (6240') BONANZA - 2024 M (6640')DMEA Z _ _ 1902 M (62407 BONANZA 1890 M (6200') YELLOW PINE PIT (Au ZONE) - 1902 M (6240') BONANZA 1 Z 890 M (6200') YELLOW PINE PIT (Au ZONE Z 1 (6200') YELLOW PINE PIT (Au ZONE) p 1890 M 1890 M (6200') YELLOW PINE PIT (W ZONE) 1890 M � 6200') YELLOW PINE PIT (W ZONE (6200' ) PIT YELLOW PINE n 1890 M (W ZONE) y 1890 M (62001 YELL PINE PIT (Sb ZONE) f W)W 18gp M (6200') YELLOW PINE PIT (Sb ZONE ) (62001) YELLOW PI 1890 M NE PIT (Sb ZONE) Figure 12a, b, and c. Bar graphs shuwink contents at selected sar _ _ 1 detection. Patterns are explained in h (b) Tc, and (c) Zn cont iK. 9. nple locations. AA= atomic absorption, E s ec= p emissions spec,, 1,1) =lunit of COOKRO, SILBERMAN, BERGER Only four samples from the nonmineralized sample suite had Ag contents above the limit of detection of 0.5 ppm; they ranged from 1 -5 ppm. None of these four samples was from high elevation; rather all were from near the access road. Copper, lead, and zinc The Yellow Pine district mineralization does not have a strong base metal component. Copper (Fig. 13) is irregularly distributed in the district. The highest concentrations are in carbonate units in the lower West End Mine (100 and 2,000 ppm) although those same carbonate rocks are not good hosts for Au. Copper is present in concentrations as high as 200 - ppm in jasperoid samples from the Fern Mine and concentrations as high as 300 ppm -in the Yellow Pine W zone. Copper contents are near crustal average for the samples from most other locations, including the unmineralized samples. Lead (Fig. 13) is generally at low concentration levels, only two samples contain more than 100 ppm, both from the Yellow Pine Mine W and Sb zones. Zinc (Fig. 12c) concentration in most rocks is at or below crustal averages, but the Fern Mine jasperoids have the highest concentrations (up to 110 ppm). Tellurium Although detectable concentrations are very spotty, high Te values (Fig. 12b) occur in the altered granitic rocks of the Au, Sb, and W zones of the Yellow Pine Mine and the upper pit of the West End Mine. The highest value we found was 5.6 ppm in a sample from the upper pit of the West End Mine. Most of the Te is at low elevation in the Yellow Pine Mine. Nearly all unmineralized samples contain less than the lower determination limit of 0.1 ppm Te. Barium and Strontium Barium content (Fig. 14b) of most samples is at or below crustal average concentrations for the lithology. Barium contents of 500 to 1,000 ppm are common at both the Yellow Pine Mine and the West End Mine. Barium content of a few jasperoid samples from the Fern Mine are greater than 100 ppm (about average for carbonates), but the maximum is only 300 ppm. Barium anomalies are common in some carbonate- hosted disseminated gold deposits, or the jasperoids associated with them, but the range of values is large (Hill and others, 1986) and fully encompasses the Ba contents at the Fern Mine. Barium content of unmineralized samples is highest in the high - elevation samples collected near the Fern Mine where skarn, marble, and schistose sandstone contain 500 ppm Ba, as opposed to the 50 to 300 ppm Ba detected in the Fern jasperoids. Strontium content (Fig. 14c) is highest in the W zone of the Yellow Pine Mine, and somewhat lower in the lower pit of the West End Mine. Unaltered igneous rocks (granite from the edge of Yellow Pine pit, felsic dikes from the access road) appear to be enriched in Sr relative to crustal averages. The Au and Sb zones at the Yellow Pine Mine have little Sr in comparison to the W zone ( the sample that contained 1,000 ppm Sr from the Sb zone is a late dike, not part of the ore). Manganese Epithermal precious -metal systems frequently exhibit Mn haloes around the ore deposits (Silberman and Berger, 1986; Berger and Silberman, 1986). Although detailed sampling has not been done at Yellow Pine, the Mn contents (Fig. 15a) of samples from the Au and Sb zones at Yellow Pine and the West End Mines are generally lower than those in the unmineralized samples collected for background, parricularly along the access road. The high Mn samples from the Au and Sb zones of the Yellow Pine Mine are from late dikes that cur the altered granitic host rock. Manganese contents of samples from the lower pit at West End are higher than those of samples from the upper pit. The highest Mn contents occur in skarn and marble, but these are not much greater than crustal average for those lithologies. The Mn 604 $ @ (§ ). \ \ \ /\ \� ƒ\ /\ \ \ 2$ 9\ / e rb @ E \\ 2 § } \rb , ; ƒ; \' \ II \@ 6 � 96 ( m $ $ ? /\ / � � { j & / \ J ( / § ƒ ° R 3 �. x 2 & / � � lir ƒ \ x / \ P7- § rD / U S " Q 2 » < m / GG ƒ 9 2 g § - 0 \ z ) r G m /G7 n 3 @ % 3 / rb .,I § ƒ } § \'� § § \ ) _ $ / § \ � % \ C ƒ Ila rD o z 0 \ 4 7 Q / a } @ _ m \ $ z m \ / / k � GB f SG* $ m ; C) \ ) 7 7 / m ƒ/ ? /\ 0 / i R § " ° a ƒ & / \ J ( / § ƒ ° R 3 �. & / f ƒ \ x / \ P7- § rD / ( » < m / / M \ ) \ \ ) r G /G7 n 3 @ rb .,I § ƒ \ \'� § § _ $ / CL \ � % \ C ƒ Ila rD PPM 1.0 • 10 100 • Sr E SPEC ••• 10 •• • 2438 M :111 •11 •11• • 2438 M •• 1000 :1.1 2438 M (8000) FERN MINE 2170 1 • PIT (UPPER) 1 1 PIT (UPPER) 2170 1 • PIT (UPPER) 1 •:1• • 2073 M (68001 WEST END - '• 1 •:1• • PIT rr•,, ° • ' �' rJ�' Y `i�yl..•!{ASSyaSla'iaY...!h�Y.. •':b:9'iSti 1 24 M (6640')DMEA YJ•l.;r.•;•} tr.:�Jy:•:•r8•:riFfeY 1 •••1 • 1902 M (62409 err • ...� ,F'�s".�J!. '•�' 1 (6640')DMEA H.1WMM1�'.•'i�.'4�'1M11+ •J'lf.: 1 1 • ' • : • , • • Va54! ?.r?iS•Yd�kby4kY4•.X•y 1902 • • BONANZA • '1 • •1 YELLOW ZONE) '1 • •• YELLOW � :v 1 • YM1S:i:•i�! %iia' •�.a e��.a ., • .•�'J� ��{, y{, , „ii{i • • �i {..y.,.�rii SJr�• :91 M (6200') YELL• ZONE) 01 YELLOW PINE PIT (W • ''r • ry , 1 . e'rY.,.....��i�.. rig rr 1890 M (62001 YELLOW •Y'•;r;�'�''d � •V • • f •, •'i ih/ •i'• ryti��S. • '•4KY7dliiriy,�!i•� ' • • , i,�,A•�•,,.Y �I/ ZONE 1890 M [6200') YELLOW PINE PIT :!a } }J' h �• {�;,• • �f'�':�I.A:tiY.T.'31. i , .•r y}� l�i j,i•�'1 • • NE) 162001 • :. .'{: YT:: S•}: rdS ::rfr }A +r:::tirr{::•:rff.:frffA t •. 1890 M, ,.,...,.........,� • • :: 1 ....flJi�htiSSK!►� • {'',•: ^: {4h, ,,•' % {4hY.Y. {y.;r YELLOW PINE PIT fSb ZONE) figure b, and c. Rat graphs showing (a) B, (b) Ba, and (c) Sr contents at selected sample locations. E Spec= - explained d in , Fig• ). P stops, spec LL>- limit of detection. Patterns are YELLOW PINE MINING DISTRICT of those lithologies lack Cr. Boron contents (Fig. Zia) of samples from the Au zone at Yellow Pine and the lower pit at West End are slightly higher than those in samples from other mineralized areas, although the ranges for these two groups overlap. The B contents (Fig. 14a) of the jasperoids at Fern are generally lower than those of other mineralized zones. White (1981) suggested that B concentrations occur in the upper parts of many geothermal systems that host precious metals. This is not the case for the Fern Mine, although many of the other epithermal trace elements occur in abundance. Summary of the Geochemistry There is some indication of metal zoning by elevation in the Yellow Pine district, but it is not as simple as has been suggested in the earlier studies. The high background values for Hg, As, and Sb throughout the district certainly suggest that the entire area was subjected to hydrothermal activity. This activity most likely was fracture controlled and produced greater concentration of these and other metals in the zones where fractures, and breccia are well - developed. 1890 M 1890 M 1890 M YELLOW PINE PIT (Au ZONE) 00') YELLOW PINE PIT W ZONE) PPM Cr E SPEC 10,000 1.0 LD 10 100 1000 11111 1 1 . . _....... _ 2438 M (8000') FERN MINE 2170 M (7120') WEST END PIT (UPPER) 2073 M1(68000') WEST END PIT (MAIN) 2024 M (6640')DMEA 1902 M (6240') BC'JANZA 1890 M (6200') YELLOW PINE PIT (Au ZONE) (6200') YELLOW PINE PIT (W ZONE) PINE PIT (Sb ZONE) 1890 M (6200') YELLOW PINE PIT (Sb ZONE) Figure 15a and b. Bar graphs showing (a) Mn and (b) Cr contents at selected sample locations. E spec = emissions spec.. I.D =limit of detection. Patterns are explained in Fig. 9. 607 COOKRO, SILBERMAN, BERGER Summary plots for some of the elements that either suggest a zoning pattern by elevation or have economic significance are in Figs. 9 -16. Gold does appear to be more concentrated at lower elevations. Only one sample containing more than 1 ppm Au was found above 2073 m (6,800 ft) in the current sample set of mineralized rocks. Alternatively, Sb occurs in very high concentrations at both high and low elevations. Mercury tends to be concentrated near the upper elevations of the system, but almost all samples from the Yellow Pine district are strongly enriched in that element. Thallium is present in abundance only at high elevations. Arsenic tends to be concentrated at moderate to low elevations, although a single sample from the Fern Mine contained >10,000 ppm. Zn, while very 'irregularly distFibuted, tends to be more consistently present at high elevations (in the Fern jasperoids�. Fluorine, not discussed earlier, is present in strongly anomalous concentrations at moderate -to high - elevations, rather than at low elevations. For the unmineralized samples, only Hg appears to show a slightly elevated content at higher elevations. La E SPEC 10 L 100 1000 2438 M L20001 FERN MINE 2170 M (7120') WEST END PIT (UPPER) 2073 M (6800') WEST END PIT (MAIN) 2024 M I (6640')DMEA 1902M[(6240') BONANZA PPM Co E SPEC 10.000 1.0 LD 10 1890 M (6200') YELLOW PINE PIT (Au ZONE) 1890 M (6200') YELLOW PINE PIT (W ZONE) 1890 M (6200') YELLOW PINE PIT (Sb ZONE) 2438 M 100 1000 RN MINE 2170 M (71201 WEST END PIT (UPPER) 2073 M (6800') WEST END PIT (MAIN) 2024 M (6640')DMEA 1902 M (6240') BONANZA 1890 M (6200') YELLOW PINE PIT (Au ZONE) 1890 M (62001 YELLOW PINE PIT (W ZONE) (ND) 1890 M 1 (62001 YELLOW PINE PIT (Sb ZONE) Figure 16a and b. Bar graphs showing (a) La and (b) Co content from selected sample locations. E spec= emissions spec.. LD =limit of detection. Patterns are explained in Fig. 9. 608 YELLOW PINE MINING DISTRICT Conclusions The paragenesis of Au- Ag -W -Sb mineralization in the Yellow Pine mining district is complex. The analytical techniques yielded results that appeared contradictory at first glance. Petrographic and geochemical data show that fractures are the major control on the deposition of metals. 40Ar /39Ar and K -Ar age determinations suggest that at least two different alteration events, rather widely spaced in rime, late Cretaceous and Eocene. Oxygen isotope and deuterium/ hydrogen isotopic ratio data suggest that fluids of deep origin or evolution and meteoric dominant origin were active in mineralization. A fluid inclusion survey suggests that epithermal processes were dominant in the development of the sulfide - scheelite concentrations, and the sulfide - scheelite deposition probably occurred at temperatures less than 200 °C ( Cookro and Silberman, 1987; Cookro, unpub. data 1987). The trace -metal assemblage, Au, Ag, As, Sb, Hg, and W, is characteristic of epithermal precious -metal deposits (Berger and Eimon, 1983), but vertical trace -metal zoning throughout the district is more complex than predicted by epithermal trace -metal zoning models or than suggested by previous authors. The primary reason zoning in the district differs from that predicted by previous models is that the silica -rich fluids, which transported and deposited sulfide - scheelite concentrations, were convecting along widely - altered, north - trending regional faults (Fig. 17a) and those faults continued to move throughout the depositional history. Mineralization is concentrated along these north - trending faults and their associated easterly trending deflections and splays where movement (or an easterly torque) caused more open brecciation. Late Cretaceous and Eocene plutons coalesced at depth along the active faults. When meteoric fluids (Fig. 16b) collected and flowed in along the faults they were heated at depth, causing them to circulate toward the surface (Fig. 16c). Since fluid flow to the surface is greatest in the zones of more open brecciation, concentrated metal deposition occurred in those zones. Movement along the faults disturbed an "ideal" zoning pattern which might have developed in a more stable system. Each displacement event changed the local pressure - temperature regime and the pattern of flow along the faults, causing a series of overprinting events. Gold deposition in the district was not specifically controlled by one process. Gold is associated with pyrite, arsenopyrite and stibnite; it also occurs as free gold. The gold - related sulfides, in albite and adularia veins which contain arsenopyrite and pyrite, could be either deep metamorphic or epithermal; textural relationships are not clear. Adularia veining, which is commonly associated with near - surface low- temperature conditions, began while albitization was still occurring. Some albite veins cross -cut adularia veins, but the more common relationship is late adularia veins cross - cutting albite veins. Both albite and adularia veins occasionally contain flakes of sericite. Sericite from a quartz vein at Yellow Pine was dated by Snee (unpub. data, 1986) as Late Cretaceous. Gold - related sulfides also occur in epithermal quartz, which contain pyrite, arsenopyrite and stibnite. Hydrothermal calcite and Mn and Fe oxides are also a part of the epithermal phase in the Yellow Pine district. Finally, free gold is present in vugs with euhedral quartz in the district and in oxidized ore at the West End Mine. Lasmanis (1981) reports gold in the oxidized ore to be along fractures and disseminated throughout. Less is known about silver in the district. Cooper (1951) reports it most closely associated with stibnite, whereas this study shows it is erratically associated with antimony and arsenic. Lewis (1984) identified miargyrite with the stibnite at the Yellow Pine Mine. Silver is also evident in some of the oxidized zones where stibnite is absent. A few of our unmineralized samples of granodiorite carry traces of silver. On the basis of present evidence, we conclude char the silver probably was deposited only by epithermal processes. 609 COOKRO, SILBERMAN, BERGER A Figure 17a. Generalized block diagram of the regional geology in the western part of the Challis l ox2° quadrangle. The right - lateral faults have a wide zone of alteration along them. A =Idaho Batholith, B= Terriary volcanic rocks of the Thunder Mtn Caldron Complex, C= metamorphic inclusions within the batholith, D =late phases ( ?) of the Idaho Batholith. l C Figure 17b and c. Generalized block diagrams of the geology in the Yellow Pine district. Rock units A through D are explained on Fig. 17a; rock unit E =small Tertiary plutons ( ?), suggested by the presence of Tertiary plutons shown on Fig. 3 in a black pattern. These granitic plutons crop out at the surface and are on strike with the NE- trending regional faults. They are north of the district but are evidence of what could be present at depth in the district, b= Surface and ground waters collect along the north - trending faults and convect upwards upon heating at depth. c =The zones of highest fluid flow of upward- moving heated fluids are those areas opened by east - trending secondary faults or where the main fault splays to the east (as happened at the Yellow Pine Mine where the fault passes through a large block of metamorphic rock). 610 YELLOW PINE MINING DISTRICT All of the tungsten within the deposits described in this paper is closely associate quartz with textures characteristic of a shallow, is skarns within the district which contain scheelite are another matter and d with low-temperature environment. Tungsten this environment. Tungsten may have been leached from some of the skarns, carrie rich fluids, and redeposited in the epirhermal environment at the Yellow are not related to and Quartz Creek Mines. The scheelite at these mines a rat always related d by silica - and at the Yellow Pine Mine was deposited very close in time a' Pine, Golden veins, ed to lace quartz veins, scheelite- stibnite- bearing quartz veins at the mine. There is also latent phase of there are deposition (Cookro, unpub. data 1987, and Petersen, 1984) which consists of tin scheelite grains on Mn oxides. s scheelite Stibnite, which no longer is a economic ore mineral, is the result of the Y al phase e of mineralization. It is closely associated with scheelite at the Yellow Pine Minermal phase found in minor quantities at other mines in the district. A favorable site f replacement in meta- argillire occurs at the Yellow Pine Mine, where the only Meadow Creek fault warps over to the east massive stibnite replaced these stibnite he north - trending scheelite replaced crystalline, hydrothermal calcite in the matrix of breccias.hese rocks, while Mercury, as cinnabar, occurs in trace quantities throughout the district. It is considered have been deposited during the epirhermal process of mineralization because it is f open pockets and in jasperoids. A possible very late stage of hydrothermal activit ma to included the H ound in Hg mineralization at the Fern Mine, which affected rocks at the highest presently exposed elevation of our sampling. Y Y have shallow manifestation of the epithermalphase lf mine aliozation. Fern Mine could also be a Sphalerite, a trace mineral throughout the district, is included in dee metamorphic quartz and is probably related to the Late Cretaceous pluton Mul however there ism is sphalerite veining in the district at the Quartz Creek Mine and the P plutonic or are associated with clear quartz typical of the epithermal environment rather than the kind of e Train claims that quartz of the metamorphic event. At the Quartz Creek Mine sphalerite concentrations occurs below the level of scheelite concentrations. There are probably several genetic models which can be used to explain the spatial relationships of mineralization- alteration and the isotopic and geochemical data. The m we feel that best explains the data involves ac least two, and perhaps mot P 1 hydrothermal events. The first event of late Cretaceous age, was related to the odic P e, epigenetic of Idaho Batholith emplacement and resulted in the deposition of early sulfides gold associated with albite and adularia veinin gold completely understood, but faulting was an important factor. The original mineralization are not deep origin, either magmatic or metamorphic, or had undergone high temperature isotopic fluids were of equilibration with meramorphic or batholithic rocks. Sericite, albite, and adularia are minerals deposited during this early phase of mineralization. In the Eocene, another stage of hydrothermal activity occurred, probably near the time of volcanism which was of Challis age. Regionally, this activity produced large areas of meteoric- in cells in the Cretaceous batholirhic rocks centered around Eocene intrusi Gold- silver epirhermal deposits occur along the margins of these large cells (Criss and Taylor, 1983). Alternatively, the meteoric-hydrothermal cells may have been centered on ons. ylo Tertiary plutons localized along major faults, similar to the Tertiary small northwest of the Yellow Pine district (Fig. 2). The epirhermal phase l in is at the surface, district might be related to this later Eocene event. Tertiary dikes in the district are the only he Yellow Pine surface expression of the Eocene event, and our field evidence shows no correlation between the shallow, low- temperature mineralization and the dikes. The hydrothermal activity Yellow Pine resulted in the deposition of metal-bearing y at scheelite, arsenopyrire, pyrite, and cinnabar are associ Gold, distinctly epirhermal character. Isotopic ated with quart and quartz veins of ratios indicate partial equilibration of earlier formed 611 COOKRO, SILBERAL4N, BERGER alteration minerals (muscovite, sericite, adularia) and document the presence of a meteoric - dominated fluid (by evidence of the D/H ratios in quartz fluid inclusions). The metals were deposited along the faults and their associated splays; the process was most efficient in zones of open brecciation or where the faults splay to the east. Alteration associated with this stage of activity was sericitization, argillizarion, and silicification. Repeated episodes of brecciation and mineralization along the shears, evidenced by the physical nature of the zones described earlier, supports the low temperature interpretation. Because second phase of mineralization took place at relatively low temperatures and we lack geochronological data on specific stages of the mineralization, we cannot specify their precise timing or duration. Acknowledgments We would like to thank Bob Perkins, Bruce Harvey, and Mike Wolford of Superior Mining Company for their help and support, and Karen Lund and Larry Snee of the U.S. Geological Survey for their timely review of the paper and their helpful criticisms. Ben Leonard (USGS) was very helpful in introducing us to the district and in providing historical information, as well as providing his geologic map which was used in the compiled map (Fig. 4). A special thanks to Don White of the U. S. Geological Survey for our discussions on Yellow Pine when he visited the area in the 1940's and now, and also his thoughtful evaluation of our ideas. Our thanks also to Diane Jones and Loretta Ulibarri for editing the paper and drafting figures, respectively, and to Yolanda Clausen for her clerical support in producing the manuscript. References Cited Armstrong, R. L., 1975, The geochronometry of Idaho: Isochron /West, no. 15, 51 p. Berger, B. R., and Silberman, M. L., 1986, Relationships of trace - element patterns to geology in hot spring - type precious metal deposits, in Berger B. R. and Bethke P. M., eds.: Geology and Geochemistry of Epithermal Systems: Reviews in Economic Geology, v. 2, p. 233 -247. Berger, B. R., and Eimon, P.,I., 1983, Conceptual models of epithermal precious metal deposits, in Shanks W. C., ed.: Society of Economic Geologists, Symposium on Unconventional Resources: p. 191 -205. Bohlke, J. K., and Kistler, R. W., 1986, Rb -Sr, K -Ar and stable isotope evidence for the ages and sources of fluid components of gold- bearing quartz veins in the northern Sierra Nevada foothills metamorphic belt, California: Economic Geology, v. 81, p. 296 -322 Cater, F. W., Pinckney, D. M., Hamilton, W. B., Parker, R. L., Welden, R. D., Close, T. J., and Zilka, N. T., 1973, Mineral resources of the Idaho primative area and vicinity, Idaho: U. S. Geological Survey Bulletin 1304, 43 p. Chao, T. T., Sanzolone, R. F., and Hubert, A. E., 1978, Flame and flameless atomic - absorption determination of tellurium in geological materials: Analytica Chimica Acta, v. 96, p. 251 -257. Cookro, T. M., and Silberman, M. L., 1987, Low temperature and low pressure sheelite at the Yellow Pine mining district-. Geological Society of America Abstracts with Programs 1987, v. 18, no. 6, p. 571 -572 (Annual Meeting, San Antonio, Texas]. Cooper, I. R., 1951, Geology of the tungsten, antimony and gold deposits near Stibnite, Idaho: U. S. Geological Survey Bulletin 969 -F, p. 151 -197. 612 YELLOW PINE MINING DISTRICT Criss, R. E., Ekren, E. B., and Hardyman, R. F., 1984, Casto ring zones: a 4500 km2 fossil hydrothermal system in the Challis volcanic field, central Idaho: Geology, v. 12, P. 331 -334. Criss, R. E., and Taylor, H. P., 1983, An 18 0/16 O and D/H study southern half of the Idaho barholirh: Geological Society of America ca Bulletin hydrothermal . 94, o. 5 systems 6 the Criss, R. 94, no. 5, p. 6- �0.6G3. E•, Lanphere, M. A., and Taylor, H. P. Jr 1982, Effects of regional uplift, deformation, and meteoric - hydrothermal metamorphism on K -Ar ages of biotires in the southern half of the Idaho barholirh: Journal of Geophysical Research, v. 87, P. 7029.76. _ Criss, R. E., 1980, An "O/,60 D/H and K -Ar study of the southern half of the Idah o barholirh: Pasadena, California Institute of Technology, Ph.D. dissertation. Dalrymple, G. B. and Lamphere, M. A. 1969, to geochronology: G. B. to Potassium argon dating, principles, techniques and a gY: W. H. Freeman and Co., San Francisco, 250 p, q applications Epstein, S., and Taylor, H. P., Jr., 1968, Variation of 1110/160 Research in Geochemistry: , N. in minerals and rocks, in Abelson, P. H. y John Wiley and Sons Inc., N. Y,, v, 2 � , ed., p• �9 -62. Evernden J. F., and Kistler, R. W., 1970, Chronology of emplacement of Mesozoic barholirh complexes in California and western Nevada: U. S. Geological Survey Professional Paper 623, 43 p. Fisher, F. S., McIntyre, D. H., and Johnson, K. M. Idaho: U. S. Geolological Survey 1983, pGeologic map of the Challis 1 ., 2 maps, scale 1:250,00 °x2° Y pen -file R eport 83 -523, 41 quadrangle, Fournier, R. O., 1986, The behavior of silica in hydrothermal solutions, in Berger . ger B. R., and Bethke P. M. eds.: Reviews in Economic Geology, v. 2, p. 45 -59. Gammons C. H., Rose, A. W. Snee, L. W., Lund, Karen, 1985, Paragenesis, fluid inclusions, and Ar -Darin of the Big Creek mining district, Valley Co., central Idaho: Geological Society of America Abstracts with Programs, v. 17, n. 7, g P. 588. Grimes, D. J., and. Marranzino, A. p, spectographic field methods for the lserniquuantitac vreanalysis and of geolog calternating materials: US. current s p ark emission Survey Circular 591, 6 p. Geological Hardyman, R. F., 1985, The Twin Peaks caldera and associated ore deposits of the Challis 1 °x 20 q uadrangle, Idaho: U. S. Geological Survey Bulletin 1658, p. 97_105. Harrison, T. M. Armstrong, R. L., Naeser, C. W., ad Hal, J. E., 1979, GeochrOnogy an thermal history of the "coast plutonic complex, near PrincenRupert,r British Columbia: Canad an Journal of Earth Sciences, v. 16, no. 3, p. 400 -410. Earth Hart, S. R., 1964, The petrology and isotopic mineral age relations of a contact zone in the Front Range, Colorado: Journal of Geology, v. 72, p. 493 -525. Hill, R. H., Adrian, B. M., Bagby, W. C., Bailey, E. A., Goldfarb, J. data for rock samples collected from selected sediment-hosted �d ssem�ina ed preeccious metal deposits in Nevada: U. S. Geological Survey Open -file Report 86 -107, 30 p J , 1986, Geochemical Hopkins, D. M., 1977, An improved ion- selective electrode method for the rapid determination of fluori ne in rocks and soils: U. S. Geological Survey Journal of Research, v. 5, no, 5 P. 583 -593. Hubert, A. E., and Lakin H. W., 1973, Atomic- absorption determination for tha Ilium and indium logic in geologic materials, in Jones M. J., ed.: Geochemical Exploration Symi and Metallurgy, London, England, P. 383.387 posum 1973, Institution Mining Kerrich, B., and Fryer, B. J., 1979, Archean precious metal hydrothermal systems, Dome Mine, Abitibi greenstone belt: 11. REE and Oxygen Isotope relations: Canadian Journal of Earth Sciences, v. 16, no. 3, p. 440 -458. 613 COOKRO, SILBERMAN, BERGER Kiilsgaard, T. H., and Lewis, R. S., 1985, Plutonic rocks of Cretaceous age and faults in the Atlanta lobe of the Idaho batholith, Challis Quadrangle: U. S. Geological Survey Bulletin, 1658 -B, p. 29 -42. Larsen E. S., and Livingston, D. C., 1920, Geology of the Yellow Pine cinnabar- mining district, Idaho: U. S. Geological Survey Bulletin 715, p. 73 -83. Lasmanis, R., 1981, West End gold deposits, Yellow Pine mining district, Idaho: preprint, 87th Annual Northwest Mining Association Convention, Spokane, Wash., 13 p. Lee, D. E., Friedman, Irving, and Gleason J. D., 1984, Modification of D values in eastern Nevada granitoid rocks spatially related to thrust faults: Contributions to Mineralogy and Petrology, v. 88, p. 888 -290. Lee, D. E., Friedman, Irving, and Gleason, J. D., 1985, The oxygen isotope composition of selected quartzites+ of White Pine county, Nevada: U. S. Geological Survey Open -file Report 86 -38, 8 p. Leonard, B. F., 1973a, The Thunder Mountain district, in Cater F. W., Pinckney, D. M., Hamilton, W. B., Parker, R. L., Welden, R. D., Close, T. J., and Zilka, N. T.: Mineral Resources of the Idaho Primative area and Vicinity, Idaho: U. S. Geological Survey Bulletin 1304, 43 p. Leonard, B. F., 1973b, Gold anomaly in soil of the West End Creek area, Yellow Pine District, Valley County, Idaho: U. S. Geological Survey Circular 680. Leonard, B. F., 1983, The Golden Gate tungsten deposit and metal anomalies in nearby soils and plants, Yellow Pine district, Valley County, Idaho: U. S. Geological Survey Open -file Report 83 -835, 26p. Leonard, B. F., and Marvin, R. F., 1982 (1984), Temporal evolution of the Thunder Mountain caldera and related fractures, central Idaho, in Bonnichsen, Bill and Breckenridge, R. M., eds.: Cenozoic Geology of Idaho, Idaho Bureau of Mines and Geology Bulletin 26, p. 23 -41. Lewis, R. D., 1984, Geochemical investigations of the Yellow Pine, Idaho and Republic, Washington mining districts: West Lafayette, Indiana, Purdue University, Ph.D. thesis, 204 p. Lund, Karen, Snee, L. W., and Evans K. V., 1986, Age and genesis of precious metals deposits, Buffalo Hump District, Central, Idaho: Implications for depth of emplacement ui quartz veins: Economic Geology, v. 81, p. 990 -996. Magham, J., R., 1984, The geology and mineralization of the Sunnyside mine, Thunder Mtn. Idaho: preprint, Annual Northwest Mining Association Convention, Spokane, Wash., 5 p. McIntyre, D. H., and Johnson, K. M., 1985, Epithermal gold - silver mineralization related to volcanic subsidence in the Custer graben Custer county, Idaho, in McIntyre D. H., ed.: Symposium on the geology and mineral deposits of the Challis 1 °x2° quadrangle, Idaho: U. S. Geological Survey Bulletin 1658, p. 109 -115. McNerney, J. J., Buseck, P. R., and Hanson, R. C., 1972, Mercury detection by means of thin gold films: Science, v. 178, p. 611 -612. Mitchell, P. A., Silberman, M. L., Oneil, J. R., 1981, Genesis of gold vein mineralization in upper Cretaceous turbidite sequence, Hope- Sunrise district, Southern Alaska: U. S. Geological Survey Open -file Report 81 -103, 20 p. Mitchell, V. E., and Bennett, E. H., 1979, Geologic map of the Elk City quadrangle, Idaho: Idaho Bureau of Mines and Geology, Geologic Map series, Elk City 2° quadrangle, scale 1:250,000. O'Leary, R. M., and Meier A. L.. 1984. Analytical methods used in geochemical exploration: U. S. Geological Survey Circular 948, p. 51 -55. Petersen. M. A., 1984, Geology and mineralization at the Quartz Creek tungsten mine, Yellow Pine, Idaho: Kent, Ohio, Kent State University, M.S. thesis, 80 p. 614 YELLOW PINE MINING DISTRICT Pollard, P. J., and Taylor, R. G., 1985, Tin deposits-' modelling and target generation: unpublished notes to accompany short course Toronto, Canada, September, 1985_ Ross, C. P, 1934, Correlation and interpretation of Paleozoic stratigraphy in south - central Idaho: Geological S of America Bulletin, v. 45, p. 937 -1000. ouery Shenon, P. J., and Ross, C. P., 1936, Geology. and ore deposits near Edwardsburg and Thunder Mountain, Idaho Bureau of Mines and Geology Pamphlet 44, 45 p• Idaho: Silberman, M. L., and Berger, B. R., 1986, Relationship of trace element patterns to alteration and morphology n epirhermal precious -metal deposits, in Berger, B. R., Bethke, P. M., Epirhermal Systems, Reviews in Economic Geology, 2, > > eds.. OieOlt'gY and Geuchemisr�} of gY, P. _03 -_37. Silberman, M. L., Berger, B. R., and Koski, R. A., 1974, K -Ar age relations of granodiorite, tungsten, and g o Id mineralization near the Gerchell mine, Humboldt County, Nevada: Economic Geology, v. 69, p 646 -656. Snee, L. W., Lund, Karen, and Evans, K. V., 1985, 40 Ar /39 At age spectrum data for the Buffalo Hum district, Clearwater Mountains central Idaho: U. S. Geological Survey Open -file Report 85 -0102 Hump mining Taylor, H. P., Jr., 1968, The ox P 8 P Petrology, oxygen isotope geochemistry of igneous rocks: Contributions w Mineralogy and gY, v. ll, 6 1 Th Taylor, H. P. Jr., 1974, The applications of oxygen and hydrogen isotope studies to problems of hydrothermal alteration and ore deposition: Economic Geology, v. 69, p 843 -883 Vaughn, W. W., and McCarthy, J. H., Jr., 1964, Au instrumental technique for the determination of submicrogram concentrations of mercury in soils, rocks, and gas, in Geological Survey Research, 1964: U. S. Geological Survey Professional Paper 501D, p. D123 -D127. White, D. E., 1981, Active geothermal systems and epirhermal ore deposits: Economic Geology 75th Anniversary Volume, P. 392 -423 White, D. i,'1945, Geologic map of the Yellow Pine district, Valley County, Idaho: U. S. Geological Survey Preliminary Strategic map, Strategic Minerals Investigarion, scale 1:48,000, text (6 P•)• White, D. E. 1940, Antimony deposits of a part of the Yellow Pine district, Valley County, Idaho: U. S. Geological Survey Bulletin 922 -1, P. 247 -279. Viets, J. G., 1978, Determination of silver, bismuth, cadmium, copper, lead, and zinc, in geologic materials by aromic- absorption spectrometry with tricapryylmethylammonium chloride: Analytical Chemistry, v. 50, 1097 -1101. P• 615 Y COOKRO, SILBERAfAN, BERGER Appendix A Sample Descriptions Tungsten Ore Zones Yellow Pine Pit 1890 m (6,200 ft) M002: strongly brecciated and altered, silicified granitic rock: vuggy with euhedral quartz, sulfides and scheelite common, calcite veins, stibnite, pyrite, arsenopyrite, sphalerite M010: strongly brecciated and altered, silicified granitic rock: sulfides and scheelite common, cp'lcire veins, stibnite, arsenopyrite, pyrite M032: strongly brecciated and altered, silicified granitic rock: sulfides and scheelite common, calcite veins stibnite, arsenopyrite, pyrite M034: strongly brecciated and altered, silicified granitic rock: sulfides and scheelite common, calcite veins, stibnite, arsenopyrite, pyrite M111: strongly brecciated and altered, silicified and sericitized granitic rock: sulfides and scheelite common, calcite veins, stibnite, arsenopyrire, pyrite M113: strongly brecciated and altered, silicifed granitic rock: sulfides and scheelite common, secondary calcite stibnite, arsenopyrite, pyrite M130: strongly brecciated and altered, silicifed granitic rock: sulfides and scheelite common, secondary calcite stibnite, arsenopyrite, pyrite Yellow Pine Mine Au Zone 1890 in (6,200 ft) Y1: silicified, sericitized granitic rock containing quartz veinlets: calcite veins, sulfides common, arsenopyrite, pyrrhorite YIA: quartz vein: sulfides common, calcite veins, sribnite, arsenopyrire pyrite, pyrrhotire, chalcopyrite Y1B: quartz - pegmatite veins: some sericire alteration, sulfides present Y1C: quartz larite dike: sulfides present YID: sericitized pegmatite dike: sulfides common, secondary calcite, beryl, arsenopyrite YIE: silicified, sericitized, granite with quartz veinlets: sulfides and scheelite present, arsenopyrite Yellow Pine Mine Granodiorite 1890 m (6,200 ft) Y2: sericitized granodiorite with pegmatite veins: some beryl and minor sulfides, some stibnite Yellow Pine Mine Sb Zone 1890 in (6,200 ft) Y3A: sericitized granitic rock with quartz veinlers: sulfides common, stibnite, arsenopyrite, pyrite Y313: sericitized granitic rock: secondary calcite, sulfides present stibnite, magnetite, pyrrhotire Y3C: sericitized, silicified granitic rock: sulfides present (disseminated) sribnite Y313: sericirized, granitic rock: sulfides present, secondary calcite stibnite, pyrrhotite Y4: diabase dike: secondary quartz veins cutting dike, arsenopyrite, pyrite, magnetite 616 YELLOW PINE MINING DISTRICT West End Upper Pit 2170 m (7,120 ft) YSA: quartzite YSB: quartzite: limonite, muscovite, K- feldspar, chlorite and tourmaline are minor consti present tuents, magnetite YSC: quartz vein in quartzite: biotite, chlorite and magnetite are minor constituents, magnetite present YSD: talc silicate skarn: diopside, calcite, quartz, actinolite and garnet Y50 ): porphyritic rhyolire with quartz veinlets Y5(2): porphyritic rhyolite with quartz veinlets: barite vein cross cutting dike DMEA Prospect (also called SULFIDE #10) 2024 m (6,640 ft) Y6: biotite felsite: calcite veins cut dike Y6A: brecciated granitic rock: calcite and quartz veins, scheelite, arsenopyrire, stibnite, pyrite Background Sampling, Access Road Near Yellow Pine Mine 2146 m (7,040 ft) Y7: Mn- and Fe -rich fault gouge Y7A: silicified quartzite: some vugs lined with euhedral quartz Y7B: silicified quartzite: very fine grained unidentified opaque minerals West End Mine, Main Pit 2073 m (6,800 ft) Y8: schist: Mn- and Fe- oxides, graphite present YBA: quartzite: Mn- and Fe- oxides, quartz, microcline, tourmaline, and pyrite minor constituents, arsenopyrire and pyrite in cross - cutting veins YBB: clay - pyrite- bearing fault gouge, in marble Y8C: argillized dike: biotire and chlorite minor, very fine grained groundmass, fine grained opaques YBD: silicified marble with quartz veins: stibnite, pyrrhorite, Y8D(1): silicified marble with quartz veinlets: pyrrhorite, fine grained opaques Background Samples Y9: amphibolite: very fine grained, biotite present 2121 m (6,960 ft) Y9A: Mn- and Fe -oxide -rich quartzite 2121 m (6,960 ft) Y10: schist: tremolite, quartz, K- feldspar, tourmaline 2121 m (6,960 fr) Y11: skarn: actinolite, quartz, serricirized plagioclase and sphene 2268 m (7,440ft) Y12: silicified marble with quartz veins: some quartz veins are chalcedony, fine grained opaques 2218 m (7, 280f t ) Y12A: Mn- and Fe -oxide -rich schist: quartz, biotire (chlorite),sillimanice 2218 m (7?80ft) Y1 3A: skarn: quartz, diopside, tremolite- actinolite, phlogopite, plagioclase, epidore, zircon, fine - grained unidentified opaques 207; in (6,800 ft) 617 Fern Mine 2438 m (8,000 ft) COOKRO. SILBERMAN. BERGER Y14: jasperoid: chalcedony vugs lined with euhedral quartz, chlorite stibnite, sphalerite ,zircon arsenopyrite, graphite, Y14A: jasperoid: chalcedony, y vugs lined with euhedral quartz, sphalerite Y14B: argillized, silicified limestone: punky texture Y14C., chalcedonic fumerole lining: chalcedony, vugs lined with euhedral quartz ve com YND: Mn- and Fe- rich -clay fault gouge rY mon, sphalerite YNE: vuggy jasperoid Y14F: silicified limestone: sheared, Mn- and Fe- oxides Y14(1): jasperoid Background Samples Y15: epidote -rich skarn: epidote in bands, calcite, k- feldspar, phlogopite, tremolite, vesu 2 vianire, quartz 646 m (8,680') Y16: marble with Mn- and Fe -oxide -rich pods: calcite, quartz, sphene fine grained opaque m (8,760 ft) minerals 2670 Y16A: marble 2670 m (8,760 ft) Y17: schistose quartzite: Mn and Fe oxide stained, quartz, biotite, sphalerite 2670 m (8,760 ft) i muscovite, sillimanre, chloriroid, Y18: sugary - textured quartzite: chalcedony, vugs lined with euhedral quartz, zircon 2706 m (8,880 ft) Y18A: black pyritic quartzite: abundant disseminated o a ues and oxides 2706 m 1'188: quartzite: vu p q (8,880 ft) ggy, Fe and Mn oxides common 2706 m (8,880ft) Y19: silicified dolomite: quartz veins, calcite /dolomite vein chalcedony veins 1877 m (6,160 ft) Bonanza Prospect 1890 m (6,240 ft) Y20: sericitized altered granitic rock: chalcedony veins, stibnite Y20A: quartz vein stockwork in carbonate: magnetite, scheelite,fine- grained opaques comm Background Samples 1890m (6,860 ft) on Y21A: Silicified dolomite with quartz veins: calcite, quartz, stockwork pattern muscovite, quartz veins and calcite veins in a W FIELD NO. M002 M010 M032 M034 M111 11113 M130 Y1 YlA Y1B Y1C YID YlE Y2 Y3A Y3B Y3C Y3D Y4 Y5A Y5B Y5C Y5D Y5(1) Y5(2) Y6 Y6A Y7 Y-/7A Y7B Y8 Y8A Y8B Y8C Y8D YBD( 1) Y9 Y9A Y10 Y11 7 Y12 7 Y12A 7 Y13 6 Y13A G Y14 8 Y14A un ELEV 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 6200 7120 7120 7120 7120 7120 7120 6640 6640 7040 7040 0 7040 p 6800 6800 6800 6800 6800 0. 6800 0.1 6960 0. 6960 0.0 6960 0.1 440 280 280 800 800 0.05 000 0.05 00 0 05 i ELLOW PINE MINING DISTRICT Appendix B Yellow Pine Quantitative Data AU HG 0.5 1.4 1.9 0.5 3.3 G 1.1 1.5 0.25 0.7 1.4 1.7 0.85 G 5.6 0.14 30 1.8 1.7 0.62 0.15 1.4 0.25 0.62 2.8 1.1 0.1 0.02 2.1 0.72 0.8 0.32 0.85 0.5 0.6 0.9 0.1 0.26 0.1 0.3 0.3 3.1 0.2 3.6 0.05 0.06 0.1 1.4 0.2 0.48 0.05 0.82 1.6 3.7 1.3 4.8 .15 0.56 05 0.56 1.7 0.62 0.3 0.36 6 0.82 0.1 1.2 05 2.3 5 4.6 p 05 G 5 1.4 5 0.92 L 1.7 L 0.58 L 0.42 L 0.42 G N G N 619 TE AS ZN SB TL F 3.5 410 25 G 0.15 i00 2.2 1200 25 G 0.9 300 7.5 580 40 G 0.35 0.25 400 15 G 1 ? 00 0.2 330 5 G 0.65 300 9 G 15 G 0.95' L 40 N G 0.05 L 5.7 G L 8 1.4 200 0.2 95 SL 46 1.1 200 0.2 1 L 5 L 8 2 2 200 0.3 G 5 12 1.6 0.7 .7 l0 5 28 2 0.2 70 1.6 G 10 4 0.2 2.2 1.8 190 160 2.2 2 0.4 90 40 G 2 1.4 1 G G 1.4 1.8 N 5 G 1.8 0.2 75 L 90 0.2 0.2 0.1 125 L 46 0.8 1.2 0.1 170 45 140 1.2 0.2 150 L 60 N 6 N L 5 N 0.6 200 .6 85 0.1 125 L 32 0.2 1 N 5 L 26 1 0.8 0.1 G L G 0.8 200 0.3 G 30 3. 100 0.1 l6 2.8 800 20 65 12 N L N 35 10 18 N 100 0.4 680 55 82 1 900 0.1 110 5 54 0.2 100 0.7 450 L 20 1.4 500 0.1 5 10 22 1.2 800 N 5 L 8 N L IV 75 L 190 N L 5 15 N 0.8 200 N 35 50 2 N L 290 20 14 0.8 300 N 0.2 300 N L L 2) N L N30 L 10 0.8 200 L L N N 300 10 5 6 N L 160 5 5-4 7.4 L 600 110 120 5.2 L 620 COOKRO, SILBER1i4AN, BERGER Appendix B Yellow Pine Quantitative Data (Continued) FIELD NO. Y14B ELEV 8000 AU HG TE AS ZN SB TL Y14C 8000 0.1 L G G N 290 35 I50 4 F 300 Y14D 8000 0.15 G N N 280 5 160 5 200 Y14E 8000 0.05 G N 950 L G 42 800 Y 14F 8000 1.5 650 40 G �'2 L . Y14(1) 8000 N G 43 N G 45 G 200 Y15 8680 N 1.9 N 350 40 120 4.2 L Y 16 8760 0.05 G N 5 G 10 N 0.4 400 Y16A 8760 N 26 N 60 980 3 L Y17 8760 N 1.7 N 10 L N N L Y 18 8880 N 1.8 N 10 5 5 N 0.6 200 Y 18A 8880 N 1.4 N 10 15 6 N L Y18B 8880 N 6.1 N 10 L 2 N L Y19 6160 1V 1 6 N 120 10 16 N L Y20 6240 N G 0.8 10 L 6 N L Y20A 6240 N G N 15 25 960 0.6 300 Y21 A 6860 0.2 1 N 20 L 60 N L .4 45 10 8 0.2 400 Yellow Pine Semi - Quantitative Data FIELD NO. M002 ELEV 6200 FE MG CA TI MN AG AS AU M010 6200 0.5 3 0.7 2 3 0.05 3000 70 1000 N B 50 BA 200 BE M032 6200 0.7 0.05 3 0.1 0.3 0.05 2000 50 1500 N 100 1000 1 1.5 M034 6200 0.7 0.2 0.3 0.1 100 300 3 700 N 70 200 1 Mill 6200 0.3 0.5 1 0.1 2 500 N 100 500 1.5 M113 6200 1 0.15 0.1 0.05 200 20 500 N 100 700 1.5 M130 Z,I 6200 0.07 3 5 0.015 5000 1 1000 2000 700 N 100 S00 1.5 YlA 6200 6200 1 0.2 5 0.2 L 0.15 20 2 5000 N 10 50 200 30 500 1 Y 1 B 6200 0.5 0.15 0.05 L 0.15 0.03 20 7 7000 20 200 500 2 2 Y 1 C 6200 5 0.5 0.2 0.15 L 3000 1.5 500 N 100 500 2 YID 6200 1.5 0.5 0.7 0.07 300 N N N 20 500 5 Y l E 6200 5 0.5 0.? 0.5 200 1 5000 N 200 500 5 Y2 Y3A 6200 S 1.5 0.5 510 5 N G N L 500 500 7 Y313 6200 6200 3 0.5 0.5 0.3 0.2 02 1>0 5 G N N 10 200 700 700 5 Z';r 6200 0.2 0.02 0? L 0.02 � 0.0_ 2 00 50 1000 L 50 300 5 1.5 YID 6200 5 0.7 0.5 0.03 L 300 20 500 N 20 200 1 Y4 6200 20 2 3 20 10000 L 200 700 2 YSA 7120 > 1 L 1 0.5 1000 1 200 N 10 1500 1.5 Y513 7120 2 0.1 0.05 0.2 100 100 2 300 N 500 1 Y5C 7120 1 0.05 L 0.03 50 1.5 1000 N 100 100 300 2 Y5D 7120 5 5 7 0. 3 1000 N 100 150 1 Y5(1) 7 2 1_0 0.5 0.02 L 0.01 1 1000 50 L N N 20 300 1.5 2 500 N 10 200 1 620 I COOKRO. SILBERMAN, BERGER Appendix B FIELD fellow Pine Semi - Quantitative Data (Continued) NO. ELEV BI CD CO M034 62pp N CR CU LA MO NB M111 62pp �' N 70 15 N NI PB SB Mill 6200 N N N 150 15 30 N L 7 L 3000 M130 6200 62pp N N N 15 30 L N N 5 L 0 Y1 600 N 2p N 200 300 50 N L � 7 N 700 Y I A- 6200 N N N 30 15 50 L N L 300 G YI 6200 N N L N 50 50 N 20 L 2p L YIC 6200 N N N N 1p 50 N L L 20 200 YID 6200 N N L N 7 100 N ?L N 20 L YIE 6200 N N 100 N 5 100 N 20 N 20 100 0 p Y2 6200 N N 10 N 15 100 N 50 N L Y3A 6200 N N 10 100 N 20 100 Y3B 6200 N N 10 N 10 200 U L 20 N YK 6200 N N N N 3p 50 N 20 L 20 200 Y3D 6200 N N N N 15 50 N 20 L 100 G Y4 6200 N N N N 20 100 N 20 L 20 10000 N N 50 200 N 20 L 30 G Y5 A 7120 N N L 30 100 L Y5B 71�p 500 7 100 0 100 30 150 YSC 7120 N N N 70 5 5p N 20 70 N 100 N N N 70 N L L L 2 Y5D 7120 L 00 N N 10 50 N L L N 100 Y5(1) 7120 N N N 150 7 50 N L 50 Y6(,) 7120 N N N N 5 50 N L L 20 100 6640 N 5 50 N 20 Y6A 6640 N N L L 50 L 20 L Y7 7040 N N N N L L 50 100 Y7A 7040 N N 2p p 15 50 N 20 N 20 100 50 Y7B 7040 N N N L 50 N L 100 20 2000 Y8 N N N N L 50 L N L 6800 N N 10 150 20 70 N L L N L Y8A 6800 Y8B N N N 20 5 50 N 20 2p L 100 G800 N N 50 100 30 50 L N L Y8C 6800 Y8D N N L N 7 100 N 20 L 50 20 L 6800 N N 20 N 100 N 20 L 50 L Y8D(1) 6800 N N 30 L N Y9 6960 N 2000 L N N 20 10 L Y9A N N 20 100 20 L 20 20 200 6960 N N 50 N L Y10 6960 N N 2p 5 50 N I. 0 L N Yll 7410 N -'0 100 5 50 L N N Y12 7280 N N 10 100 5 50 N 20 2p L L Y12A 7280 N N 10 N 7 L N 20 30 L N Y13- 6800 N N �0 200 50 N L S L SO 0 L Y13A 6800 N N 10 L 10 50 N 2 50 L L Y I -1 8000 N N L 20 15 50 N 20 10 L N Y l iA 8000 N N 50 L 30 50 N 20 5 10 L Y14 8000 N N 50 L 50 50 L 20 N 100 Y14C 8000 N N L L 5 50 10 L 20 N 200 Y 14D 8000 N N 0 20 200 50 N L L N 00 50 N 20 100 L IOOU 622 _ ( y YELLOW PINE MINING DISTRICT FIELD NO. ELEV SC SN SR V Appendix B M002 6200 7 N 500 Yellow Pine Semi - Quantitative Data (Continued) ZR TH M010 6200 FIELD N 500 100 10000 20 30 N 50 N M032 6200 L N NO. Y 14E ELEV BI CD CO CR CU LA MO NB NI PB 20 Y 14 8000 8000 N N N N N N 5 50 N L L N SB 1000 Y14(1) 8000 N N Io 20 L 50 50 N L 20 L G Y15 8680 N N � 0 N 100 20 50 N :L 10 L 100 Y16 8760 N N L N 20 50 N 1 20 20 L Y 16A 8760 N N L 50 10 50 N L 30-- L 1000 Y17 8760 N 200 100 N 150 5 50 N L to N N Y18 8880 N N ' N 30 50 N 20 50 10 N Y 18A 8880 N N N N L 50 N L L L N Y18B 8880 N N N N L 50 N L L N N Y19 6160 N N N N 7 50 N L 20 N L Y20 6240 N N N N L 50 N L N N N Y20A 6240 N N N N 10 50 N 20 N 15 G Y21A 6860 L N N N N 50 N N N L 100 N N Y5B 7120 N N 10 50 N L L 5 L L FIELD NO. ELEV SC SN SR V M002 6200 7 N 500 200 10000 ZN ZR TH M010 6200 7 N 500 100 10000 20 30 N 50 N M032 6200 L N 100 20 500 L N 100 N M034 6200 L 1!. 200 20 50 L 50 N Mill 6200 L N 300 20 5000 15 N 50 N M113 6200 L N 100 20 70 10 N 30 N M130 6200 7 N 2000 200 G 10 N N Y1 6200 N N 100 50 N 50 N N N N YIA 6200 N N N 100 N L L 100 N YIB 6200 N N 100 20 N L 200 100 N Y1C 6200 L N L 20 N L 20 N YID 6200 L N 100 20 50 N 20 L 200 N YIE 6200 5 N 100 50 50 50 L 100 N 2 6_00 5 N 500 50 20 20 L 200 N Y3A 6200 5 N 150 50 L 10 L 150 N Y3B 6700 L 20 N L 15 0 N Y3C 6200 N N L 20 N L L 20 N Y3 6200 5 10 100 100 L L L L 20 N Y4 610 00 �0 N 1000 200 N 50 L 200 100 300 N N Y5B 7120 N N 200 30 L 200 N Y5C 7120 N N 50 20 N L L 200 N Y513 71,0 15 N '0 50 N N L L 50 N Y50) 7120 L N L 10 30 L 200 N Y5(2) 7120 L N L 20 N N L L N Y6 66-40 L N 300 L N 50 L L N Y6A 6040 5 N 300 20 2000 L L 50 N Y7 70=40 Zo N N 300 100 50 70 N L 100 N 623 >% C j fir COOKRO, SILBERMAN, BERGER Appendix B Yellow Pine Semi - Quantitative Data (Continued) FIELD NO. Y7A ELEV SC SN SR V W Y ZN ZR TH Y713 7040 7040 N N N N 20 N L N L N Y8 6800 20 N N N L 20 N L N 200 N Y8A 6800 L N N 100 L 30 L 200 N Y813 'Y8C 6800 20 N 150 30 300 N L 10 20 L' 200 N 6800 10 N 500 50 N 50 L L 200 -- N Y813 6800 N N 200 50 N N N 200 N Y8D(1) 6800 N N 200 100 N N L L N 1'9 6960 20 N L 100 N 50 L L 50 N Y9A 6960 L N N 30 N L L 200 N N Y10 6960 20 N N 100 L 50 N 200 N Yll Y12 7440 20 20 200 100 N 50 N 200 N Y12A 7280 7280 N 20 N 100 20 N N N L N Y13 6800 5 N N N 100 N 50 N 200 N Y13A 6800 L N 100 500 50 10 N N 30 L 500 N Y14 8000 N N N 10 200 10 L N N 70 N Y14A 8000 N N N 10 500 L N 70 200 N N Y14B 8000 N N N 20 200 L N 150 N Y14C 8000 N N N 20 500 N N 200 N Y14D Y14E 8000 10 N N 50 200 100 N 500 N Y14F 8000 8000 N N N N 10 200 L N 100 N Y14(1) 8000 N N N N N 100 500 50 200 100 N Y15 8680 10 N 500 10 100 1000 N L L N 100 N Y16 8760 N N N 100 N N N L 100 N Y 16A 8760 N N L L N N N 150 N N Y17 8760 N N N 100 N 50 L 200 N N Y18 8880 N N N L N N N L N Y 18A 8880 - N N N L N N N L N Y18B 8880 N N N L N N N L N Y19 6160 N N N L N N N 300 N Y20 6240 N N N L N N N 100 N Y20A 6240 N N N L N N N L N Y21A 6860 L N 500 50 N N N 200 N 624