Bodie Mine

Site Name

Primary: Bodie Mine
Secondary: Bodie Project

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Commodity

Primary: Gold
Primary: Silver
Tertiary: Mercury

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Location

State: California
County: Mono
District: Bodie District

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Land Status

Land ownership: State Park
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.
Administrative Organization: Bodie State Historic Park, California Department of Parks and Recreation

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Homestake Mining
Info Year: 2007

Owner Name: Galactic Resources Ltd.
Home Office: Vancouver, Canada
Info Year: 2007
Years: 1988 - 1997

Owner Name: State of California; administered by CA State Parks in coop with the U.S. Bureau of Land Management
Info Year: 2007
Years: 1997 -

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Production

Not available

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Deposit

Record Type: District
Operation Category: Past Producer
Deposit Type: Hydrothermal sheeted stockworks, veins, local disseminations
Operation Type: Surface-Underground
Discovery Year: 1859
Years of Production:
Organization:
Significant: Y
Deposit Size: M

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Physiography

Not available

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Mineral Deposit Model

Model Name: Epithermal vein, Comstock

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Orebody

Form: Irregular, tabular

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: Propylitic Argillic Potassic Silicic

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Rocks

Name: Volcanic Rock (Aphanitic)
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene
Age Old: Miocene

Name: Granite
Role: Associated
Age Type: Associated Rock
Age Young: Mesozoic

Name: Metamorphic Rock
Role: Associated
Age Type: Associated Rock
Age Young: Mesozoic
Age Old: Paleozoic

Name: Volcanic Rock (Aphanitic)
Role: Host
Age Type: Host Rock
Age Young: Miocene

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Analytical Data

Not available

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Materials

Ore: Cerargyrite
Ore: Electrum
Ore: Silver
Ore: Gold
Ore: Argentite
Ore: Chalcopyrite
Ore: Sphalerite
Ore: Galena
Ore: Pyrite
Gangue: Quartz
Gangue: Illite
Gangue: Hematite
Gangue: Chlorite
Gangue: Adularia
Gangue: Calcite

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Comments

Comment (Geology): Tectonic Setting: Back-arc extensional cratonic basin; basin and range. Regional Structures: 1. An irregular north-south-trending anticline formed by intrusion and doming of flows and tuff breccia and small plugs; normal faults that strike generally parallel to the fold axis; normal faults that strike normal to the fold axis. 2. North-northeast-trending normal faults (generally older normal faults): a) Moyle Footwall Fault: normal; N 38 ? E strike; 60-70? east dip; down to the southeast; pre- to post-mineralization; forms west boundary of Bonanza zone and Bodie Graben. b) Standard Vein Fault: normal; N 18-20? E strik1e; 60-70? west dip; down to the northwest; pre- to post-mineralization; forms east boundary of Bonanza zone and Bodie Graben. c) Other north-northeast-trending, innamed normal faults associated with the Bodie Graben. 3. West-northwest-trending normal "cross" faults (generally younger normal faults): a) Tioga fault: normal; N 62? W strike; forms north boundary of Bonanza zone; primarily pre-mineralization with relatively small post-mineralization movement. b) Mono fault: normal with a right-lateral component; N 66? W strike; forms south boundary of Bonanza zone; mostly pre-mineralization. Alteration: Four stages commencing with propylitic and followed in succession by argillic, potassic, and silicic. Propylitic alteration is characteristic of the margins of the district; propylitically altered rocks are greenish in color and contain chlorite, epidote, various clay minerals, albite, pyrite, and minor quartz. Argillic and potassic alteration sequences occurred later and were more pervasive. Argillically altered rocks are generally light colored and contain montmorillonite, illite, sericite, quartz, and pyrite. Potassically altered rocks are only locally light colored, and tend to resemble the original rock in color and texture; they show extensive development of adularia, quartz, sericite, and pervasive, irregular veins of quartz-adularia, with or without calcite. Silica-altered rocks are light colored, hard, and form a capping on argillically altered rocks. Ore control: Normal faults and associated fractures, possibly related to doming, at the center of extrusive volcanic activity (small dacite plugs). Texture/Structure: Fissure veins, banded veins, open-space fillings, parallel sheeted stockworks, local disseminations. Depth of mineralization: Mineralization in the Bodie District appears to be shallow, and precious metals values rarely extended much lower than the 500-foot level in any mine. The Fortuna vein is an exception and was mined to a depth of about 600 feet below the surface.

Comment (Economic Factors): HISTORIC PRODUCTION (McCluskey, written communication, Report to Sierra Mines, Inc., 1947, cited in Chesterman and others, 1986, pg. 31; metric tons and grade were calculated by this MRDS reporter): Reported historic production from the Bonanza zone (area of Bodie Project) is more than 633,000 oz Au (19.7 metric tons, 1.67 oz Au/ton) and as many as 800,000 oz Ag (24.9 metric tons, 2.11 oz Ag/ton) from approximately 380,000 tons of ore No production resulted from the Bodie Project.

Comment (Geology): Geology (continued) Tuff breccia within the Bodie Graben has been down-dropped against the intrusive dacite along the northeast-striking faults. Many small blocks of uplifted and down-dropped intrusive dacite and tuff occur within the graben structure. Faulting probably occurred during and shortly after intrusion of the dacite, and ore deposition was partly controlled by the graben structure, commencing after intrusion of the dacite plugs. The major mines of the district are located within and near the Bodie Graben. The productive quartz veins cut both tuff breccia and intrusive rocks. Most of the mineralization, however, is confined to the intrusives. There are several sets of quartz veins, varying in thickness from less than a foot to as much as 90 feet, although most veins are not more than a few feet thick. The major veins generally strike north to northeast with variable dips of 45-90 degrees. The veins are chalcedonic to fine-grained quartz fracture fillings and are discontinuous near the presently exposed top of the system at Bodie Bluff. Between 100 and 200 feet below the present land surface, the veins grade into typical banded, sheeted, bonanza-type veins. Ore minerals are principally native gold and electrum, but argentite, cerargyrite, chalcopyrite, galena, pyrite, and sphalerite also occur. Major gangue minerals include quartz and adularia, with minor calcite, chlorite, hematite, and illite. Detailed logging, geochemical analysis and fire assaying of diamond drill core and rock chip samples indicate that precious metal mineralization is primarily confined to quartz and quartz-adularia veins and veinlets. Old records from the main productive zone near the Bodie Graben indicate the ore averaged 1.75 oz Au/ton and 3.1 oz Ag/ton (Au:Ag = 1:1.77). Much of the mineralization identified by drilling occurs as 1/8-inch to 2-inch gold-silver-bearing veins and veinlets, in contrast to the major, thick quartz-adularia veins and bonanza zones. Adularia samples from mineralized quartz veins have returned ages ranging from 8.0 to 7.1 m.y. B.P. Hydrothermal alteration started at 8.6 m.y. B.P., as dated by K-Ar ages of sericite from altered tuff breccia in the southern part of the district and potassium-silicate-altered Bodie Bluff intrusive dacite. Alteration is zoned both laterally and vertically. At Bodie Bluff, in the northern part of the district, intrusive dacite and tuff breccia flows are strongly silicified at the surface. It has been suggested that this silicified zone, a part of which has chalcedonic quartz vein stockworks and intense hydrothermal brecciation, represents a very shallow level in the original system. This interpretation is supported by the small deposits of sinter found along the western edge of the Bodie Graben at Bodie Bluff. Below this surficial alteration, the rocks of the Bodie Bluff area are strongly potassium silicate-altered, as evidenced by the assemblage of K-feldspar (adularia), K-mica (sericite), and quartz. Pyrite occurs throughout the system in a variety of settings. This alteration suite is also prevalent in the wall rocks of the main mineralized productive zone. Outcrops east of the Bodie Bluff intrusive are also strongly potassium-silicate- altered. Brecciation in these outcrops suggests near-surface cooling, with geochemical signatures similar to Standard Hill, where altered rocks are enriched in Hg, As, Sb, and Tl. Oxidation of sulfides, and argillic and sericitic alteration occur south of Bodie Bluff. On and around Standard Hill, oxidation is weakly to moderately pervasive. Strong argillic alteration occurs in shear zones south of the Mono Fault, and extends 10s of feet beyond the shear zones, especially on Silver Hill. Silicified breccia cropping out on Silver Hill appears to be related to the shearing. Outside of the central part of the district, most of the rocks are moderately to strongly propylitized.

Comment (Commodity): Ore Materials: Native gold, native silver, electrum, argentite, cerargyrite, chalcopyrite, galena, pyrite, sphalerite, sulfosalts

Comment (Geology): Geology (continued) Studies of the alteration, geochemistry, isotope distribution, and styles of mineralization identified at Bodie, are indicative of a paleo-geothermal hot springs system with bonanza veining. Fluid inclusion temperatures and salinity determinations indicate that mineralization and alteration were produced by heated meteoric waters similar to currently active geothermal fluids in the Bodie Hills area. The veining and alteration assemblages are typical of a prograde geothermal system. The veins at Bodie display episodic sulfidic silicification typical of such systems. In the main bonanza zone, the veins are spatially related to a small andesitic to dacitic intrusion. The veins range in width from <1 m to 30 m, and occupy north- to northeast-trending, steeply dipping fractures. Crustiform textures, cross-cutting relationships, and multiple stages of brecciation indicate that ore deposition was a result of multiple hydrothermal events that occurred between 8.0 and 7.1 Ma. Average ore grades in the bonanza veins were about 60g Au/ton and 100g Au/ton. These veins consist mostly of quartz with smaller amounts of adularia, pyrite, argentite, sphalerite, native gold and native silver. Gold enrichment occurs in veins to a depth of about 200 m, below which base metal and silver sulfides and sulfosalts become more important. Near the surface and at shallow depths, silicification and fracture-controlled potassic alteration are overprinted and surrounded by argillization, resulting in a quartz-adularia-illite assemblage adjacent to veins. This assemblage is typical of the main bonanza veins. Peripheral to the productive area and at greater depths, the volcanic rocks have been pervasively propylitized. Based on fluid inclusion studies, temperatures of ore deposition and solution salinity were 215?-245?C and <0.5 wt.% NaCl equivalent, respectively. Such a solution would boil at a depth of about 400 m (Haas, 1971, cited in Bromberger, 1993). Herrera (1988, cited in Bromberger, 1993) documented the occurrence of sinters and explosion breccias in proximity to the veins, and concluded that ore deposition at Bodie occurred in a paleogeothermal center similar to many present-day not spring systems. This suggests that the present-day surface is not too far below the paleosurface at the time of ore formation, and that the latter occurred at a rather shallow level, perhaps at or less than the depth of boiling (Bromberger 1993, pgs. 81-82).

Comment (Economic Factors): DEPOSIT SIZE Medium, based on post-historic-mining reserve estimates (current remaining reserves) of 52.7 and 41.6 metric tons gold (Homestake Mining, 1988): 1. Based on a cutoff grade of 0.020 oz Au/ton, the Bodie Mine deposit contains a total of 24,568,000 tons probable + possible + inferred reserves with average grade 0.069 oz Au/ton = 1,695,192 oz Au (52.7 metric tons Au). 2. Based on a cutoff grade of 0.040 oz Au/ton, the Bodie Mine deposit contains a total of 12,394,000 tons probable + possible + inferred reserves with average grade 0.108 oz Au/ton = 1,338,552 oz Au (41.6 metric tons Au). Medium (needs to be checked), based on historic gold production + remaining gold reserves (72.4 metric tons) (McCluskey, written communication, Report to Sierra Mines, Inc., 1947, cited in Chesterman and others, 1986, pg. 31; Homestake Mining, 1988. pg. 5): Historic production 633,000 oz Au (19.7 metric tons) Reserves (0.020 oz Au/ton cutoff grade) 1,695,192 oz Au (52.7 metric tons) Total 2,328,192 oz Au (72.4 metric tons) Estimated total silver mined + remaining reserves in the Bodie Project area: Historic production 800,000 oz Ag (24.9 metric tons) Reserves 10,316,040 oz Ag (320.8 metric tons) Total 11,116,040 oz Ag (345.7 metric tons)

Comment (Environment): The historic Bodie town site is managed by the California State Parks. The Bodie Hills area surrounding the project includes the Bodie Bowl, designated an Area of Critical Environmental Concern in 1993 by the U.S. Bureau of Land Management. The Bodie Protection Act of 1994 prohibited the Bodie Bowl from being available for any mineral mining, leasing, or disposal activities, except under valid existing claims. The historic mining town of Bodie, the Bodie Bowl, and the Bodie Mine (aka Bodie Project), are administered by California State Parks and the U.S. Bureau of Land Management, in cooperation with Mono County and various environmental interest groups. The purchase of the Bodie Project by California State Parks in 1997 ended all future development of the mineral resources in the Bodie Project area.

Comment (Economic Factors): RESERVES (Homestake Mining Co., 1988): Mineral inventories were calculated using three classifications and a cross-sectional method. For each cutoff grade the following classifications were used (Homestake Mining Company, 1988): " Probable - maximum projection of assay data is 100 feet beyond the drill hole intercept, up and down dip, as well as along strike in both directions or halfway to the next data point, whichever is less; " Possible - projection of assays is from 100 to 200 feet beyond the intercept, or half the distance to the next data point, whichever is less; " Inferred - projection of assays is greater than 200 feet beyond the intercept or halfway to the next data point, where geologic evidence suggests such a projection has merit. The mineral inventory for the Bodie Bluff and Standard Hill targets was calculated using gold cutoff grades of 0.020 oz Au/ton and 0.040 oz Au/ton. Bodie Bluff Area Standard Hill Area Total Tons Au Ag Tons Au Ag Tons Au Ag Mineral Inventory - 0.020 Au cutoff (tons X 1000) Probable 1,642 0.064 0.30 4,152 0.073 0.56 5,794 0.071 0.48 Possible 2,384 0.065 0.28 4,583 0.073 0.61 6,967 0.070 0.50 Inferred 5,335 0.068 0.25 6.472 0.065 0.41 11,807 0.066 0.34 Total 9,361 0.067 0.27 15,207 0.070 0.51 24,568 0.069 0.42 Total 1,695,192 oz Au (52.7 metric tons) Mineral Inventory - 0.040 Au cutoff (tons X 1000) Probable 846 0.097 0.38 2,134 0.117 0.76 2,980 0.111 0.65 Possible 1,178 0.100 0.38 2,180 0.123 0.83 3,358 0.115 0.67 Inferred 2,810 0.102 0.29 3,246 0.104 0.53 6.056 0.103 0.42 Total 4,834 0.101 0.33 7,560 0.113 0.68 12,394 0.108 0.54 Total 1,338,552 oz Au (41.6 metric tons) Minimal drilling was done outside the identified target areas, allowing for potential expansion of the Bodie Project resource in untested areas. Chesterman and others (1986) reported an estimated 25,000,000 tons ore with an average value in 1947 of $1.86 per ton remaining in the Bonanza zone.

Comment (Commodity): Gangue Materials: Quartz, adularia, calcite, chlorite, hematite, illite,

Comment (Economic Factors): GOLD/SILVER RATIO Total reserve estimates for the Bodie Project (Homestake Mining, 1988, pg. 5) give average ore grades of 0.069 oz Au/ton and 0.42 oz Ag/ton (cutoff grade 0.020 oz Au/ton), and 0.108 oz Au/ton and 0.54 oz Ag/ton (cutoff grade 0.040 oz Au/ton), which yield Au/Ag ratios of 1:6 and 1:5, respectively. Old records from the main productive zone near the Bodie Graben indicate the ore averaged 1.75 oz Au/ton and 3.1 oz Ag/ton (Homestake Mining, 1988, pg. 3), an Au/Ag ratio of 1:1.8. Veins in the Standard Hill area (area of Bodie Graben) in 1883 yielded an average of 1.65 oz Au/ton and 3.14 oz Ag/ton (Chesterman and others, 1986, pg. 30), an Au/Ag ratio of 1:1.9 The Bonanza zone yielded more than 633,000 oz Au and as many as 800,000 oz Ag (from S. B. McCluskey, written communication, cited in Chesterman and others, 1986, pg. 33), an Au/Ag ratio of 1:1.3. The ratio of gold to silver by weight in the northern part of the district was about 1:12 (Chesterman and others, 1986, pg. vii). Presumably, this includes the Bodie Bluff and Standard Hill areas. Records of production from the Bodie District prior to 1877 are essentially non-existent, and data after that date are sketchy. Past production is estimated at about 1.25 million tons yielding 1.5 million ounces of gold and more than 15 million ounces of silver (Homestake Mining, 1988, pgs. 1-2), an Au:Ag ratio of 1:10).

Comment (Location): Longitude and latitude represent the top of Standard Hill located 0.53 miles N 57? E of the junction of Bodie Road and Union Street in the center of the historic mining town of Bodie, CA. Standard Hill is located near the center of the Bodie Mine (aka Bodie Project). Bodie can be reached: a) by traveling 9.5 miles south from Bridgeport, CA, on Interstate Hwy 395, then 12.3 miles east on State Hwy 270 (paved & unpaved); or b) by traveling 11.2 miles north on State Hwy 270 (unpaved) from its junction with State Hwy 167 north of Mono Lake. Unpaved portions of "Hwy 270" shown on some maps may be part of the county road network. Hwy 270 to Bodie is closed in winter. The site of the historic gold camp of Aurora, NV, is approx. 12.5 miles 8.8 air miles N 52.8? E of Bodie; the historic gold camp of Masonic, CA, is about 11.1 miles N 35? W of Bodie.

Comment (Development): YEAR OF DISCOVERY 1859, by early prospectors; in 1976, Homestake began comprehensive exploration (the Bodie Project) for a bulk-mineable, precious-metals deposit in the area of Bodie Bluff and Standard Hill, the historic Bodie District's Bonanza zone. EXPLORATION AND DEVELOPMENT 1859-late 1890s: The Bodie District was discovered in 1859, reportedly by several prospectors who were working shallow placers in the east-central part of the district. Gold-bearing quartz veins were discovered later that summer. In 1860, the mining district was organized and named "Bodey" after one of the prospectors, William S. Bodey, who died in a blizzard. In 1862, the spelling was changed (by accident or otherwise) to "Bodie". The first mining company was organized in 1863 when owners of several adjacent mines consolidated their claims and holdings to form the Bodie Bluff Consolidated Mining Company with Governor Leland Stanford as President and Judge F. T. Bechtel as Secretary. Production peaked during the late 1870s and early 1880s and declined until the late 1890s when the cyanide process and electricity were introduced to the district. A resurgence of production followed; much of the activity centered on the re-working of tailings and dumps. Almost as much gold was produced from this re-working as was initially recovered in the old stamp-amalgamation mills. Records of production prior to 1877 are essentially non-existent, and data after that date are sketchy. Past production is estimated at about 1.25 million tons yielding 1.5 million ounces (46.66 metric tons) of gold and more than 15 million ounces (466.55 metric tons) of silver (a gold/silver ration of 1/15). Most of the ore was produced from a relatively thick sequence of shallow dipping veins known as the Bonanza zone, from stopes up to 90 feet in height. 1928-1932: the Treadwell-Yukon Company (Homestake Mining, a silent partner) began evaluating the northern part of the district. No study was made of the central Bonanza Zone, which had caved shut in the late 1880s. More than 10,000 samples reportedly were taken from surface and underground, with almost half of the samples posted on work maps covering over 10,000 feet of crosscuts and drifts. Based on this data, it was estimated, in 1945, that potential existed for as much as 76 million tons of "marginal ore" with an approximate grade of 0.05 oz Au/ton (3,800,000 oz Au, 118 metric tons) and 0.75 oz Ag/ton (57,000,000 oz Ag, 1773 metric tons). This mineralization was thought to occur as parallel, sheeted stockworks of veins and local disseminations around and within the Bodie Graben. The estimate included nearly 25 million tons remaining in the former principal production area between the Standard New and the New Bodie shafts. A limited program of dump and open pit mining was conducted for confirmation of assay results, which met with reported success. 1935-1942: Roseklip Mines was formed in 1935 to treat dumps in the district. They instead, mined approximately 55,000 tons of material from the site of the Treadwell-Yukon pit between 1935-1942. Underground sampling by Treadwell had indicated that the ores in the area of the pit should average about $1.75/ton ($35.00/ounce Au price) or 0.0494 oz Au/ton. The returns from the Roseklip Pit were reportedly $1.71/ton or 0.0488 oz Au/ton. 1942-1945: WWII interrupted mining in Bodie. 1961-1966: the Bodie Historic Mining District is designated a National Historic Landmark in 1961. The State of California had begun purchasing the townsite form the Cain Company and other owners in the late 1950s; in 1962, Bodie became a State Historic Park. In 1966, the town of Bodie is named to the National Register of Historic Places.

Comment (Development): EXPLORATION AND DEVELOPMENT (continued) 1993-1997: Galactic Resources declared bankruptcy, and the company's Bodie property interests were placed in the hands of a Canadian bankruptcy trustee. Following nearly three decades of increasing environmental and political activism focused on the Bodie area, the California Desert Protection Act, which created the Mojave National Preserve and establised the Bodie Protection Act of 1994, was signed into law. The Act required that existing mineral claims be reviewed, and that claims found to be valid be subject to regulations no less stringent than those administering mining within National Parks. The Act also required the Department of the Interior to carry out a study as to how Bodie could be further protected "including but not limited to acquisition of lands?" In cooperation with the Bureau of Land Management, the National Park Service, and private funding sources, California State Parks secured state, federal, and private funding, which met the requirements of the Galactic bankruptcy trustee. In 1997, California State Parks consummated an agreement for the purchase of Galactic's interests in the Bodie Project. This purchase ended all future mineral development of the Bodie Mine/Bodie Project. Current Land Status: The historic mining town of Bodie and surrounding areas, including the Bodie Mine, aka Bodie Project, are administered by California State Parks and the U.S. Bureau of Land Management, in cooperation with Mono County and various environmental interest groups. The purchase of Bodie Project lands by California State Parks in 1997 ended all future development of the mineral resources in the Bodie Mine/Bodie Project area. Development Status: In cooperation with the Bureau of Land Management, the National Park Service, and private funding sources, California State Parks purchased all of Galactic Resource's interests in the Bodie Property in 1997. This purchase ended all future mineral development of the Bodie Mine/Bodie Project). Metallurgy (Homestake Mining Company, 1988): Bottle roll testing conducted on 70 to 85 percent minus 200 mesh material in 1985 and 1986 indicated that gold and silver respond well to direct cyanidation or bulk sulfide flotation. Gold extraction was, however, found to be significantly better with leaching as compared to flotation. Column leaching returned gold recoveries of 78 to nearly 95 percent, and silver recoveries of 33 to 100 percent. In 1987, 113 day leach rest cycle column leach tests performed on minus ?-inch and minus 1-inch core, gave recoveries ranging from 78.2 to 92.3 percent for gold and 33.2 to 64.8 percent for silver. Three 4 ?- to 5-foot columns, each 6 inches in diameter, containing 16 to 18 kg of crushed ore, were used for the testing. Early milling (Chesterman and others, 1986, pg. 33): The first ore mined in the Bodie District was milled in arrastras; some ore was hauled to Aurora, NV, and processed in stamp mills. The Bodie ores were characterized as "free-milling"; a large percentage of the gold was recoverable in the free and relatively pure state by amalgamation or strake (shaking table) concentration. Silver occurs in the gold and as sulfides or as the chloride, cerargyrite; in the early 1900s, it was found that Bodie ores were amenable to simple cyanidation. The process yielded high extraction with relatively low costs and low consumption of reagents.

Comment (Geology): Derived largely from Silberman, 1985; Chesterman and others, 1986; Homestake Mining Company, 1988; Romberger, 1993. Introduction The Bodie Mining District is located in eastern Mono County, CA, in an area known as the Bodie Hills, a high desert in the rain shadow of the Sierra Nevada Range. The district has produced more than $34 million in gold and silver from fissure veins in Miocene volcanic rocks of intermediate composition. The district is centered on Sections 9, 10, 16, and 21, T 4 N, R 27 E. The early Bodie townsite or "ghost town", now a California State Historic Park, is situated at an elevation of 8,350 feet. Bodie Bluff is the highest point in the district at 9,005 feet. Winters are often extremely cold, and snow levels vary greatly both within the district and from year to year. The Bodie Project area is located along and immediately southeast of the ridge that forms Bodie Bluff and Standard Hill. The northern and southern portions of the Bodie Project are called the Bodie Bluff Target Area and Standard Hill-Bonanza Target Area, respectively. The Bodie Project area coincides with the Bodie Graben and the historic Bonanza zone. More than 90 percent of the ore from the lode deposits in the Bodie District reportedly came from historic mines in the Standard Hill area.

Comment (Geology): Geology (continued) Age of Mineralization: " Late Miocene, between 8.0 m.y. B.P.and 7.1 m.y. B.P. (Silberman, 1985; Homestake Mining, 1988). Host Rock Age: " the Silver Hill Volcanics, andesitic to dacitic flows, tuff breccias, and small intrusive plugs: Late Miocene, 9.4-8.6 m.y. B.P. (Chesterman and Gray, 1966, cited in Silberman, 1985; Silberman, 1985; Homestake Mining, 1988). [Volcanic activity in the Bodie Hills spanned the time interval 13.3-5.7 m.y. B.P.; most eruptive material was emplaced between about 9.5 and 7.8 m.y. B.P. (Silberman, 1985).] Associated Rock Types: " Pre-Tertiary metamorphic rocks are not exposed in the Bodie Hills but crop out elsewhere: pre-Cretaceous gneiss and schist at Masonic Mountain 12 miles northwest of Bodie (Koenig, 1963, cited in Chesterman and others, 1986); Paleozoic(?) and Mesozoic(?) quartzofeldspathic hornfels and greenstones east and northeast of Conway Summit 12 miles southwest of Bodie (Chesterman, 1968, cited in Chesterman and others, 1986). " Pre-Tertiary Granitic rocks occur in the Bodie Hills and are generally intrusive into pre-Cretaceous metamorphic rocks: Cretaceous (93.4 m.y.) biotite granite east of Conway Summit (Chesterman, 1968, cited in Chesterman and others, 1986); presumably pre-Cretaceous body of granitic rock whose composition ranges from granodiorite to quartz monzonite at Masonic Mountain (Koenig, 1963, cited in Chesterman and others, 1986). " Younger post-ore sequence of volcanic rocks, east of Bodie Mining District, 3.6-0.25 m.y. B.P. (Silberman, 1985). " Younger rhyolitic rocks, western Bodie Hills, 5.7-5.3 m.y. B.P. (Silberman, 1985). " Murphy Spring Tuff Breccia, 8.9-8.7 m.y. B.P. (Chesterman, 1968, cited in Silberman, 1985). " Potato Peak Formation (interlayered dacite flows and tuff breccia of dacitic composition), 9.1-8.4 m.y. B.P. (Chesterman, 1968, cited in Silberman, 1985). " Other basalt-andesite-dacite-rhyolite, western Bodie Hills, 13.3-7.8 m.y. B.P. (Silberman and others, 1972, cited in Silberman, 1985). Associated Rock Age: " Pre-Cretaceous gneiss and schist (Koenig, 1963, cited in Chesterman and others, 1986); Paleozoic(?) and Mesozoic(?) quartzofeldspathic hornfels and greenstones (Chesterman, 1968, cited in Chesterman and others, 1986). " Cretaceous (93.4 m.y.) biotite granite (Chesterman, 1968, cited in Chesterman and others, 1986); pre-Cretaceous granodiorite to quartz monzonite (Koenig, 1963, cited in Chesterman and others, 1986). " 3.6-0.25 m.y. B.P. post-ore volcanic rocks. (Silberman, 1985). " 5.7-5.3 m.y. B.P. rhyolitic rocks (Silberman, 1985). " 8.9-8.7 m.y. B.P. Murphy Spring Tuff Breccia (Chesterman, 1968, cited in Silberman, 1985). " 9.1-8.4 m.y. B.P. Potato Peak Formation, interlayered dacite flows and tuff breccia of dacitic composition (Chesterman, 1968, cited in Silberman, 1985). " 13.3-7.8 m.y. B.P. basalt-andesite-dacite-rhyolite, western Bodie Hills, Silberman and others, 1972, cited in Silberman, 1985). Host Rock Unit: Silver Hill Volcanic Series. Host Rock Unit Age: 9.4-8.6 m.y. B.P. (Chesterman and Gray, 1966, cited in Silberman, 1985; Silberman, 1985; Homestake Mining, 1988).

Comment (Deposit): The geologic setting of the Bodie District consists of Tertiary-age calc-alkaline and bimodal volcanism and associated intrusive activity over pre-Tertiary metamorphosed sedimentary rocks [pre-Cretaceous gneiss and schist; Paleozoic(?) and Mesozoic(?) quartzofeldspathic hornfels and greenstones] that have been intruded locally by pre-Tertiary granitic rocks (Cretaceous biotite granite; pre-Cretaceous granitic rocks ranging in composition from granodiorite to quartz monzonite). Studies of the alteration, geochemistry, isotope distribution, and styles of mineralization identified at Bodie are indicative of a paleo-geothermal hot springs system with bonanza veining. Fluid inclusion temperatures and salinity determinations indicate that mineralization and alteration were produced by heated meteoric waters similar to currently active geothermal fluids in the Bodie Hills area. The veining and alteration assemblages are typical of a prograde geothermal system. The veins at Bodie display episodic sulfidic silicification typical of such systems. In the main bonanza zone, the veins are spatially related to a small andesitic to dacitic intrusion. The veins range in width from <1 m to 30 m, and occupy north- to northeast-trending, steeply dipping fractures. Crustiform textures, cross-cutting relationships, and multiple stages of brecciation indicate that ore deposition was a result of multiple hydrothermal events that occurred between 8.0 and 7.1 Ma. Average ore grades in the bonanza veins were about 60g Au/ton and 100g Au/ton. These veins consist mostly of quartz with smaller amounts of adularia, pyrite, argentite, sphalerite, native gold and native silver. Gold enrichment occurs in veins to a depth of about 200 m, below which base metal and silver sulfides and sulfosalts become more important. Mineralization in the Bodie District appears to be shallow, and precious metals values rarely extended much lower than the 500-foot level in any mine. The Fortuna vein is an exception and was mined to a depth of about 600 feet below the surface.

Comment (Development): EXPLORATION AND DEVELOPMENT (continued) 1968-1969: Since the onset of bulk-mining of low-grade ores in the late 1960s to early 1970s, several companies drilled and explored Bodie's mineralized system. ASARCO sampled some of the underground workings around Bodie, and drilled approximately 39 holes. 1972-1974: Phelps-Dodge performed underground sampling and drilled 10 holes in the northern part of the district. 1976-1978: In the fall of 1976, Homestake began an exploration program, which included 63 drill holes, as well as extensive surface mapping and sampling, and metallurgical testing. A total of 49 holes were drilled by others prior to Homestake's involvement in the district. 1978: California State Parks released the Bodie State Historic Park Resource Management Plan, General Development Plan, and Environmental Impact Report, which re-affirm that Bodie State Historic Park will be preserved in a state of "arrested decay." the General Development Plan's land use recommendations argue against open-pit mining. 1983: Homestake farmed out its Bodie Property to NERCO, which performed a limited reevaluation of the property. 1985 -1986: Hometake drilled 11 reverse circulation holes, conducted geologic mapping and metallurgical testing, performed an internal Environmental Reconnaissance Report, and collected baseline data for a future Environmental Impact Report. Homestake offered the property up for sale soon after. 1988: At the beginning of 1988, Homestake controlled both surface and mineral rights on approximately 3 square miles in the Bodie Project area, comprising 176 unpatented and 72 patented claims in four leases. Fifty unpatented claims were held solely by Homestake. During early 1988, Homestake and Galactic Resources Ltd. of Vancouver, Canada, entered into an agreement in which Galactic purchased Homestake's entire interest in the Bodie Mining District for approximately $39,500,000. In mid-1988, California State Parks notified the National Park Service that Bodie was threatened by a potential large-scale mining operation on the bluff above the townsite. The J. S. Cain Company, Lost Carcass and Buzzard Mining Company, and other adjoining property owners had leased their mineral rights and mining claims to the Bodie Consolidated Mining Company, a subsidiary of Galactic Resources Ltd. Galactic had initiated exploration in the privately-owned Bodie Bluff and Standard Hill areas, and was securing placer mining claims on surrounding public lands managed by the U. S. Bureau of Land Management. 1991-1992: Closure and cleanup at Galactic's Summitville Gold Mine in Colorado created financial hardship for Galactic Resources. The cleanup was prompted by leaking of cyanide and acidic, metal-laden mine water into the headwaters of the Alamosa River. Galactic announced it would sell the Bodie property to pay for cyanide cleanup operations in Summitville as part of its reclamation agreement with the state of Colorado. In 1992, Summitville Consolidated Mining (subsidiary of Galactic Resources) declared bankruptcy. In 1992, the Bodie Protection Act of 1992 (HR 4370) was introduced in the U.S. House of Representatives, and California State Parks began discussions with Galactic to acquire the Bodie property.

Comment (Workings): Workings Type: the Bodie Project is a proposed open-pit mine in an area of historic primarily underground workings; more recent, relatively minor open-pit mining has occurred in the area. Description of Mine Workings: the Bodie Mine (aka Bodie Project) includes the area of historic, primarily underground mining in the Bodie Bluff and Standard Hill areas. More than 90 percent of the ore from the lode deposits in the Bodie Mining District came from historic mines in the Standard Hill area. Plate 4, showing mine workings in the Bodie Bluff - Standard Hill Area (Chesterman and others, 1968) reveals tens of thousands of feet of underground shafts, drifts, winzes, crosscuts, raises, and stopes.

Comment (Geology): Geology The Bodie Hills comprise a volcanic massif approximately 35 km3 in volume and as much as 400 m thick. The area surrounding the Bodie Hills constitutes a major volcanic province, which has been subdivided on the basis of dominant lithology and age of volcanic activity (Chesterman, 1968; Gilbert and others, 1968, and Kleinhampl and others, 1975, cited in Silberman, 1985). The Miocene volcanics, erupted from numerous stratovolcanoes ranging in composition from rhyolite to basalt, include flows, tuff breccias, tuffs, and intrusive plugs and domes. Dacite is the most common compositional type and tuff breccia the most common textural variety. Volcanic activity in the Bodie Hills area spanned the interval from 13.3 to 5.7 m.y. B.P. Mesozoic and Paleozoic metamorphosed sedimentary rocks form the basement of the Bodie Hills and surrounding region. These basement rocks are intruded and metamorphosed by granitic rocks of the Sierra Nevada Batholith. The Bodie District occupies an eruptive center, composed of dacite flows, tuff breccias, and small intrusive plugs of the Silver Hill Volcanic Series. (Silver Hill is located about 3000 feet south of the Bodie Project, area.) the Silver Hill Volcanic Series represents a local phase of an extensive suite of calc-alkaline volcanic rocks (including basalt, andesite, dacite, and rhyolite) that were erupted 7.8 to 9.5 m.y. B.P. in the region surrounding the Bodie Mining District. The plugs occupy vents from which the extrusive rocks were erupted. The Silver Hill Volcanics and the associated co-magmatic plugs were emplaced between 9.4 and 8.6 m.y. B.P. The primary regional structure in the area of the Bodie Mining District is an irregular faulted north-south-trending anticline formed by intrusion and doming of the flows and tuff breccia by small plugs. Two prominent sets of steeply dipping faults, one striking north to northeast, and a second set striking west to northwest (normal to the first set), cut all of the lithologic units, including the intrusive plugs in the district. The major ore-bearing veins and fractures strike parallel to the northeast-striking set. The most prominent structure in the Bodie Project area is the Bodie Graben developed mostly in the dacite plug in the Bodie Bluff-Standard Hill area. The main faults, the Moyle Footwall Fault and the Standard Vein Fault, strike northeasterly, generally parallel to the axial plane of the anticlinal fold, and are the west and east bounding faults, respectively, of the Bodie Graben. Both faults are normal with very little strike-slip movement, and are the west and east bounding faults of the historic Bonanza zone. Activity on the Moyle Footwall fault extended from pre-mineral into post-mineral time. The Standard Vein fault is pre-mineral in age, but with sustained post-mineral movement. There are several "cross faults" in the district that strike northwesterly generally perpendicular to axial plane of the anticlinal fold. The Tioga and Mono faults are the main cross faults in the Bodie Project area. The Tioga fault, which forms the northern boundary of the Bonanza zone, is a normal fault in which the block on the south has dropped in a near-vertical direction. The Tioga Fault is mostly pre-mineral in age; post-mineral movement along the fault was relatively small. The Mono Fault, which forms the southern boundary of the Bonanza zone, is a normal fault with vertical displacement down on the south and a component of right-lateral displacement. The major movement along the Mono Fault was pre-mineral.

Comment (Ownership): Homestake Mining sold all of its holdings in the Bodie Hills area (including the Bodie Project) to Galactic Resources Ltd., Vancouver, Canada, in 1988. All of Galactic's holdings were subsequently purchased by California State Parks in 1997. No future commercial mining operations are permitted in the Bodie Project area.

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References

Reference (Deposit): California State Parks, 2003, Guide to the Bodie Consolidated Mining Company records, Bodie State Historic Park, Bridgeport, California: California Department of Parks and Recreation Website.

Reference (Deposit): Chesterman, C. W., Chapman, R. H., and Gray, C. H., Jr., 1986, Geology and ore deposits of the Bodie mining district: California Division of Mines and Geology (aka California Geological Survey) Bulletin 206, 35 pages, 5 plates, 11 figures, 7 tables, 17 photographs.

Reference (Deposit): Clark, W. B., 1988, Bodie District, in Gold Districts of California, Sesquicentennial Edition, California Gold Discovery to Statehood: CGS (formerly CDMG) Bulletin 193, Page 147-148.

Reference (Deposit): Homestake Mining Company, 1988, Bodie Project, Mono County, California: Summary report: CGS Minefile Folder No. 322-6117.

Reference (Deposit): Huston, Ann, and Tilghman, B. N., 1997, Bodie, California, preserving a historic mining landscape: Bodie Park brochure, California Department of Parks and Recration, Resource Management Division, pgs. 41-45.

Reference (Deposit): Mosier, D. L., Singer, D. A., and Berger, B. R., 1986; Descriptive model of comstock epithermal veins, in Cox, D. P., and Singer, D. A., Mineral deposit models: U.S. Geological Survey Bull. 1693, pgs. 150-151.

Reference (Deposit): Portions of various unpublished reports, and information from various Internet websites, contained in CGS (formerly CDMG) Minefile Folder No. 322-6117 and in the CGS Sunshine Mines archives.

Reference (Deposit): Romberger, S. B., 1993, A model for bonanza gold deposits, in Sheahan, P. A. and Cherry, M. E., eds., 1993, Ore deposit models; Volume II: Geological Society of Canada, Geoscience Canada, Reprint Series 6, pgs. 81-82.

Reference (Deposit): Bodie.com: Bodie Chronology

Reference (Deposit): Silberman, M. L., 1985, Geochronology of hydrothermal alteration and mineralization: Tertiary epithermal precious-metal deposits in the Great Basin, in Tooker, E. W., ed., Geologic characteristics of sediment- and volcanic-hosted disseminated gold deposits - search for an occurrence model: U.S. Geological Survey Bull. 1646, pgs. 55-70

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California Gold

"Where to Find Gold in California" looks at the density of modern placer mining claims along with historical gold mining locations and mining district descriptions to determine areas of high gold discovery potential in California. Read more: Where to Find Gold in California.