Tonkin Springs Gold Mine

Site Name

Primary: Tonkin Springs Gold Mine

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Commodity

Primary: Gold
Secondary: Silver
Tertiary: Arsenic
Tertiary: Mercury
Tertiary: Antimony
Tertiary: Zinc
Tertiary: Barium-Barite

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Location

State: Nevada
County: Eureka
District: Tonkin Springs District

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Land Status

Land ownership: BLM Administrative Area
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: Battle Mountain District

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: U.S. Gold Corp.
Percent: 40.00
Home Office: Colorado
Info Year: 1996
Years: 1990 -

Owner Name: Gold Captial Corp.
Percent: 60.00
Home Office: Colorado
Info Year: 1996
Years: 1993 -

Owner Name: Homestake Mining Co./U. S. Gold JV

Owner Name: Homestake Mining Co.

Owner Name: US Gold Corp.
Info Year: 2006

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Production

Year: 1990
Description: Au 2735 Oz
Year: 1986
Mined: 379000.000 mt
Material type: ore processed
Description: Ore Processed 379000 Metric Tons Ore/Year
Year: 1985
Mined: 253000.000 mt
Material type: ore processed
Description: Ore Processed 253000 Metric Tons Ore/Year

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: disseminated
Plant Type: Leach
Operation Type: Surface
Mining Method: Open Pit
Milling Method: Leach-Solvent-Extract-Precipitation
Year First Production: 1985
Year Last Production: 1990
Discovery Year: 1982
Years of Production:
Organization:
Significant: Y
Deposit Size: S

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Physiography

Not available

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Mineral Deposit Model

Model Name: Sediment-hosted Au

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Orebody

Form: TABULAR

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Structure

Type: L
Description: Intercalated slices of eastern and western facies rocks comprise the upper plate of the Roberts Mountains thrust. Brecciation and recumbent folding resulting from late Devonian to Mississippian deformation are well developed within the tectonically disturbed zone between slices. En echelon NNW-striking, east dipping normal faults of Tertiary age dominate the local structural fabric. ENE-striking, near vertical normal faults are subordinate in magnitude to the NNW trend and have localized silicification in places (e.g. Rooster Ridge). A N-S to NNE structural trend is recognized on high altitude photography.

Type: R
Description: Roberts Mountains Thrust; WNW-striking broad, open folds.

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Alterations

Alteration Type: L
Alteration Text: Alteration that has affected ore host rocks includes silicification, decalcification, argillization, carbonization. Silicification is widespread throughout the district and is evidenced by abundant jasperoid. Gold ore is often found in decalcified limestone. Argillization is widespread, but argillized rocks are generally not mineralized. The amount of carbonaceous ore has now been shown to be at least in part due to finely disseminated sulfide, not carbon.

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Rocks

Name: Granodiorite
Role: Associated
Description: sill
Age Type: Associated Rock
Age in Years: 33.400000+-
Age Young: Early Oligocene

Name: Granodiorite
Role: Associated
Description: sill
Age Type: Associated Rock
Age in Years: 37.500000+-
Age Young: Middle Eocene

Name: Siltstone
Role: Host
Age Type: Host Rock
Age Young: Late Devonian
Age Old: Middle Devonian

Name: Limestone
Role: Host
Age Type: Host Rock
Age Young: Ordovician

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Analytical Data

Not available

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Materials

Ore: Barite
Ore: Gold
Ore: Arsenopyrite
Ore: Pyrite
Ore: Calcite
Ore: Quartz
Ore: Stibnite
Ore: Cinnabar
Ore: Orpiment
Gangue: Realgar

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Comments

Comment (Development): In 1993, Gold Capital attempted to modify the existing heap leach pad but ran short of financial resources. In February, 1999 it sold its interest to Agnico-Eagle. From 1993 to 1999, little exploration took place on the property. Agnico-Eagle drilled 107 reverse circulation holes and confirmed the mineral resource at Tonkin Springs. It also extended the known mineralization at various deposits on the property and discovered new gold mineralized zone at the north end of the property. Aginco-Eagle did not find enough economic mineralization to justify its goals and, in October, 2001, also withdrew from the joint venture. In 2003, BacTech acquired a 55% interest in the property from US Gold. However, BacTech was unable to fulfill the requirements set out in the agreement, giving US Gold 100% ownership over Tonkin Springs. In July 2005, Rob McEwen purchased 33% of US Gold and also assumed the position of Chairman and CEO.

Comment (Economic Factors): Reserves reported in 1987: 1.5 million tons of oxide ore grading 0.05 opt Au and 2.5 million tons of sulfide ore grading 0.09 opt Au. In 1996, reserves were reported as 9.8 million tons of ore grading 0.056 opt Au. In 1998 there were drill-defined reserves of 1.365 million ounces of Au. Production from 1987 through 1990 was 14,086 oz Au. Production of silver reported from 1989 through 1990 was 1870 oz Ag.

Comment (Development): Exploration began in the Tonkin Springs area during the 1950s and 1960s. The Rooster claims were staked in 1966 by Lyle Campbell on the basis of outcropping jasperoid. Claims optioned by several companies 1966-81, with additional staking expanding the claim block during this period. Companies which conducted exploration during that time, included Homestake Mining, American Selco, Chevron Resources, Placer Amex, Earth Resources and Freeport Exploration. These companies discovered gold mineralization but considered to be too low-grade and sporadic at that time to be of interest . Mineral Ventures, Inc. conducted a drainage sediment sampling program in 1979. Anomalous gold concentrations were identified on the Rooster claims and for several miles to the south. Drainages in the immediate vicinity of the Tonkin Springs deposit contained gold contents varying between 0.03 and 0.06 ppm. The Rob claims were then staked in 1980. Precambrian Exploration teamed with Mineral Ventures, Inc. in 1982 to explore the Rob Claims. Geologic mapping and grid soil and rock geochemical surveys defined the drill targets that became the TSP 1,3, and 4 orebodies. These shallow ore pods had coincident Au, Hg, As, and Sb soil anomalies (see Mehrtens, 1987). Silver State Mining (now U.S. Gold) optioned the property in January 1985 and put the property into production. The first gold was poured October 1985. The land position was expanded by the optioning of the Rooster claims in 1986 and claim staking in the Twin Peaks area in 1987. The claim block in 1990 encompasses approximately 42 square miles along trend. A joint venture of U.S. Gold (49%) and Homestake Mining (51%) was formed in early 1991 to further explore and develop Tonkin Springs. According to Silver State Mining 1985 annual report, total capital costs are $1.90 million, production costs are $85/oz. Au ($122/oz. Au, including depreciation, depletion, and amortization), and gold recovery rate is 70%. U.S. Gold is pioneering bio-oxidation of bulk gold ores at Tonkin Springs. From 1981 to 1985, Energy Reserves Group and Mineral Ventures continued to explore the property until their mining leases were terminated. In January, 1986 US Gold Corporation leased the property and has controlled it ever since. Exploration in the area that hosts the sulfide deposits began in 1979. At this time, Mineral Ventures conducted sampling program searching for Carlin-type gold deposits. In 1981, Mineral Ventures conducted a drilling program that encountered potentially economic mineralization at what later became known as the TSP-1 deposit. The company continued exploration drilling and, in 1985, US Gold entered into a joint venture on the property with Mineral Ventures. In 1987, US Gold bought control of the company. The drilling completed by US Gold from the mid to late 1980s delineated several more small deposits. Mining activities took place that produced over 30,000 ounces of gold, mostly from oxide ores. During the work, many roads were constructed and heap leach pad was built and operated. From 1998 to 1990, in excess of $30 million was spent constructing an on site mill. Many more claims were added to the property position and several exploration targets were found. From 1991 to 2001, US Gold teamed up with several mining companies to explore the property. Some of the companies included Homestake Mining, Gold Capital, Globex Mining and Agnico-Eagle. Each of these companies conducted an exploration program which laid out different goals. Homestake drilled 86 reverse circulation and core holes. Though several interesting showings were encountered in this drilling, Homestake determined it had not discovered a deposit that met its corporate objectives and, in 1992, it withdrew from the joint venture.

Comment (Geology): Intrusive sills of intermediate composition are spatially associated with gold deposition. Since the sills are offset by feeder faults and can be mineralized, they are believed to pre-date gold deposition. The sills may have acted as impermeable caprocks to the hydrothermal system, resulting in the localization of gold in the sediments adjacent to the intrusive.

Comment (Identification): This record is an updated record including data from M242945 and W700599, which have been deleted. It also includes all material from earlier record W700407, which could be deleted.

Comment (Location): The mine is located on the east flank of the Simpson Park Mountains.

Comment (Workings): TSP-1 pit, ore treatment facilities. In 1998 there was ongoing exploration, metallurgical testing, and mine development.

Comment (Commodity): Ore Materials: pyrite, arsenopyrite, native gold,

Comment (Commodity): Gangue Materials: realgar, orpiment, cinnabar, stibnite, quartz, calcite, barite

Comment (Deposit): Approximately 75% of gold occurs as micron-sized grains in pyrite and arsenopyrite. 25% of gold occurs as free grains in silica veinlets or along fractures.

Comment (Reserve-Resource): http://www.romarco.com/news/index.php?&content_id=131 26.5 million tonnes of measured and indicated resources grading 1.2 g/t as defined by Micon International Limited in their NI 43-101 report dated June 3, 2004 which was prepared for BacTech and can be found on www.sedar.com.

Comment (Development): http://www.romarco.com/news/index.php?&content_id=131 The Tonkin Springs Mine is a previously producing gold mine strategically located in the prolific Cortez Gold Trend of Nevada. The property package encompasses 36 square miles and has existing infrastructure including a 1,800 tonne-per-day mill on site. It is anticipated that a feasibility study will be conducted immediately for start up operations. Strategically located on the Cortez Gold Trend south of the Placer Dome:Rio Tinto Cortez Joint Venture's Pipeline deposit and the recently discovered Cortez Hills deposit In operation from 1985 to 1988 and again in 1990 Existing mill and infrastructure (+$30 million original cost) 36 square mile land package provides exploration potential

Comment (Economic Factors): OPERATING COSTS IS $172/OZ AU EQUIVALENT.

Comment (Production): 1988 PROD. = 50,000 OZ AND 1988 RESERVE = 345,071 OZ CONT.AU. (SUPPOSEDLY). 1989 BOM PROD. SURVEY SHOWS PROD. OF ONLY 1,753 OZ IN 1989 (SHUT DOWN?). QUESTION AS TO HOW MUCH RESERVE REMAINS. 1500 TO 2000 ST/DAY ORE, 1995.

Comment (Reserve-Resource): OPEN PIT; HEAP AND VAT LEACH OPERATION (INCL. BIOOXIDATION) OPERATION SHUTDOWN 1991; REPOENED 12/95; RESERVES 12/31/95.

Comment (Economic Factors): STRIPPING RATIO IS REPORTED AT 16:1, AND SHOULD REDUCE TO 5:1.

Comment (Environmental Factors): MINOR AMOUNTS (0.25%) PYRITE IN WASTE MATERIAL. SMALL AMOUNTS (0.25-0.5%) PYRITE IN TAILS.

Comment (Environmental Factors): THE TAILINGS DAM, WASTE DUMP, AND EXISTING HEAP LEACH ARE BUILT ON A THICK ZONE OF ALTERED CLAY VOLCANICS WITH VERY LOW PERMEABILITIES (10E-8 CM/SEC).

Comment (Reserve-Resource): 1991 RESERVES: OXIDE: 1.61 G/MT - 651,000 MT ORE SULFIDE: 1.21 G/MT - 636,000 MT ORE MILL: 2.58 G/MT - 2,523,000 MT ORE

Comment (Reserve-Resource): RESOURCE INFORMATION IS FROM BATTLE MOUNTAIN GOLD COMPANY, 1986 ANNUAL REPORT.

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References

Reference (Deposit): NBMG Mining District File #106, Press Clippings.

Reference (Deposit): Hardesty, R., 1983, The Tonkin Springs Gold Deposit, presentation at the 89th Annual Northwest Mining Association Convention, Spokane; copy in NBMG Mining District File #106.

Reference (Deposit): Mehrens, M.B., 1987, Case history and problem 1: The Tonkin Springs Gold Mining District, Nevada, U.S.A., in Fletcher, W.K., et al., eds., Exploration geochemistry: design and interpretation of soil surveys, Reviews in Economic Geology, vol. 3, p. 129-134.

Reference (Deposit): Silver State Mining 1985 Annual Report.

Reference (Deposit): NBMG, 1994, MI-1993, MI-96; MI-97; MI-98; NBMG Map 91, 1st, 2nd, 3rd; Amer. Mines (1998) 1997: Mas, 1984; Amer. Mines (1999), 1998.

Reference (Deposit): Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Database of significant deposits of gold, silver, copper, lead, and zinc in the United States; Part A, Database description and analysis; part B, Digital database: U.S. Geological Survey Open-File Report 98-206, 33 p., one 3.5 inch diskette.

Reference (Deposit): US Gold Corp website 2006

Reference (Deposit): Nevada Division of Mine Inspection Staff, 1988, Directory of Nevada mine operations active during calendar year 1987: 84 p.

Reference (Deposit): Benedetto, K., et al, 1992, Roadside Geology and Precious Metal Mineralization along U.S. 50, Reno To Ely, Nevada, in Buffa, R. and Coyner, A., eds., Geology and Ore Deposits of the Great Basin - Field Trip Guidebook Compendium, The Geological Society of Nevada, Reno, p. 1133.

Reference (Deposit): Eespell, R. and Rich, T., 1992, Geology and Mineralization of the Tonkin Springs Mining District, in Buffa, R. and Coyner, A., Geology and Ore Deposits of the Great Basin - Field Trip Guidebook Compendium, The Geological Society of Nevada, Reno, p. 949-958.

Reference (Deposit): Tingley and Smith, 1983, A Mineral Inventory of The Shoshone-Eureka Resource Area, Battle Mountain, Nevada: NBNG Open File Report 83-3.

Reference (Deposit): Tingley and Smith, 1983, Results of geochemical sampling within the Shoshone-Eureka Resource Area, Eureka, Lander, and Nye Counties, Nevada: NBMG Open File Report 83-4.

Reference (Deposit): Bonham, H., 1989, Bulk-Mineable Precious-Metal Deposits and Prospects in Nevada: NBMG Map 91.

Reference (Deposit): NBMG, 1988, The Nevada Mineral Industry - 1987, NBMG Special Publication MI-1987.

Reference (Deposit): NBMG, 1991, The Nevada Mineral Industry - 1990, NBMG Special Publication MI-1990.

Reference (Deposit): USGS Open-File Report 376, 1978.

Reference (Reserve-Resource): 1995/96, NEVADA MINES DIRECTORY, PP. 18, 19, 24.

Reference (Reserve-Resource): GOLD CAPITAL CORPORATION, 1995, FORM 10-KSB, P9.

Reference (Deposit): NEVADA MINING ASSOCIATION BULLETIN, ENERGY RESERVES GROUP FINDS GOLD MINERALIZATION IN EUREKA CO., OCT-NOV, 1981, VOL 3, # 6, P16.

Reference (Deposit): RANDOL, 1996/97, MININING DIRECTORY, U.S. MINES & MINING COMPANIES, P275.

Reference (Deposit): THE MINING RECORD, VOL 107, #?, AUG. 31, 1996, P9.

Reference (Deposit): THE MINING RECORD, VOL 107, #41, OCT. 9, 1996, P1.

Reference (Deposit): THE MINING RECORD, VOL 108, #16, APR. 16, 1997, P3.

Reference (Deposit): U.S. GOLD COPR., NEWS RELEASE, APR., 29, 1996.

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Nevada Gold

Nevada has a total of 368 distinct gold districts. Of the of those, just 36 are major producers with production and/or reserves of over 1,000,000 ounces, 49 have production and/or reserves of over 100,000 ounces, with the rest having less than 100,000 ounces. Read more: Gold Districts of Nevada.