Round Mountain Gold Mine

Site Name

Primary: Round Mountain Gold Mine
Secondary: Sunnyside Mine
Secondary: Sphinx Glory Hole
Secondary: Great Western Tunnel
Secondary: Rattlesnake
Secondary: Keane Vein
Secondary: Los Gazabo Vein

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Commodity

Primary: Gold
Primary: Silver
Tertiary: Antimony
Tertiary: Tungsten
Tertiary: Thallium
Tertiary: Mercury
Tertiary: Molybdenum
Tertiary: Fluorine-Fluorite
Tertiary: Manganese
Tertiary: Arsenic

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Location

State: Nevada
County: Nye
District: Round Mountain District

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Land Status

Land ownership: Private
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.

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Joint venture: Barrick Gold Corporation
Info Year: 2005

Owner Name: Joint venture: Kinross Gold Corporation
Info Year: 2005

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: disseminations; veins; sheeted zones
Operation Type: Surface-Underground
Year First Production: 1906
Discovery Year: 1906
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: Hot-spring Au-Ag

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Orebody

Form: tabular, mushroom

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Structure

Type: R
Description: NW lineament is seen as a disruption in N-S trends of Toquima and Toiyabe Ranges

Type: L
Description: Northwest-striking faults and joints; a WNW-trending paleotopographic high, may represent the margin of buried caldera located SW of Round Mountain.

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Alterations

Alteration Type: L
Alteration Text: Propylitization and argillization of host rocks are intense. Adularia replacement of K-feldspars and plagioclase is associated with ore. Plagioclase and groundmass are replaced with quartz and sericite. Within propylitically altered rock, biotite is partially or wholly altered to chlorite. Groundmass is altered to chlorite +/- clay +/- carbonate+/- epidote. Plagioclase phenocrysts are altered to sericite (illite) as small points, clots, and veinlets along cleavage planes. Argillically altered rock contains no unaltered biotite or plagioclase, both phases being altered to clay (illite, montmorillonite, kaolinite) and sericite. Groundmass is entirely composed of fine-grained clays and sericite. Quartz-adularia silicification is widespread along the veins. Degree of silicification, sericite + argillic alteration increases with (higher) elevation. Fine-grained secondary quartz has replaced original plagioclase feldspars, occurs as clots in the groundmass, and as hairline veinlets that lace the rock.

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Rocks

Name: Metasedimentary Rock
Role: Host
Age Type: Host Rock
Age Young: Paleozoic

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

Name: Ash-Flow Tuff
Role: Host
Description: rhyolitic
Age Type: Host Rock
Age in Years: 26.000000+-
Dating Method: K-Ar
Age Young: Late Oligocene

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Realgar
Ore: Fluorite
Ore: Kaolinite
Ore: Montmorillonite
Ore: Illite
Ore: Jarosite
Ore: Alunite
Ore: Limonite
Ore: Hematite
Ore: Sericite
Ore: Adularia
Ore: Quartz
Ore: Pyrite
Ore: Electrum
Ore: Scorodite
Gangue: Clay

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Comments

Comment (Commodity): Ore Materials: free gold, electrum, auriferous pyrite

Comment (Commodity): Gangue Materials: clay minerals, quartz, adularia, sericite, hematite, limonite, manganese oxide, pyrite, alunite, jarosite, illite, montmorillonite, kaolinite, fluorite, realgar, scorodite

Comment (Deposit): The Round Mountain deposit includes the Los Gazabo Vein, Keane Vein, Mariposa Vein sheeted zone, Great Western sheeted zone, Black Hawk sheeted zone, 921 Section, 471 Vein, and Fault Fissure vein. The veins were so closely spaced as to form sheeted zones; the dips of veins steepen and change with depth. Gold grade of ore has a positive correlation with the abundance of NW-striking joints. The ore-hosting tuff consists of a 400 to 500 foot thick non-welded base, a densely welded central portion about 800 feet thick, and a less densely welded vapor-phase altered top that is 75-100 feet thick. Where narrow fractures cut the lower, non-welded portion, mineralization occurs as thin quartz veinlets and as disseminations throughout the pumiceous tuff (type II ore). In the welded portion, mineralization occurs wholly as veins along high angle fractures or along hydrothermally dilated low angle joints (type I ore). Dip of the ain ore body is 15SW at cap, 85SW at base. In 1992-3, a high grade zone, 900 feet in strike length and undefined at depth, was discovered and mined. The high grade zone contained very abundant coarse gold or electrum, often crystalline, associated with sericite along a low-angle fracture. Albino and Veek both disagree with applicability of hot springs model as that model is currently described.Gold is intergrown with vein quartz associated with limonite and minor manganese oxide in small fissures. Visible gold often occurs on projecting quartz crystals in drusy cavities and is distinctly crystalline, usually in fairly well defined octahedral and more complex forms. Gold on adularia was observed in specimens from the rich veinlets on the top of Round Mountain.

Comment (Geology): Oligocene felsic volcanic rocks (tuffs) and Paleozoic metasedimentary strata host the gold mineralization. The volcanic host rocks are dated at ? 26.5 to 26.0 Ma. The geologic section for the Round Mountain mine, from oldest to youngest, is Paleozoic strata, Cretaceous granite, the Round Mountain volcanic section: 1) moderately welded, bedded tuff, 2) nonwelded, pumice-rich rhyolite tuff, 3) a transitional unit of moderately welded rhyolite tuff, 4) the densely welded rhyolite tuff, and 5) the overlying Stebbins Hill units, consisting of laminated tuffaceous lake beds, tuffs, vitrophyre, volcanic breccias and silicified breccias. The valley fill rocks consist of a lower placer gold bearing alluvial unit and an upper alluvial section with considerable granitic detritus. All of the rock units are known to contain ore except the granitic intrusion and the upper alluvium. The structural setting of the Round Mountain deposit consists of the volcanic units gently dipping to the southwest uncomformably deposited on "basement" rocks of metasedimentary Paleozoic rocks and the granitic pluton. The Paleozoic strata are tightly folded with numerous small-scale thrust faults. Faulting that cuts the Tertiary rocks trend N20?E, N45?Eand N70?W. The N70?W trend for faults and fractures is the dominant trend for mineralization. Basin and Range faults are well exposed in the pit and have an orientation of approximately N20?E/65-75?W. These faults are well exposed in the pit and have been intersected in the current underground exploration workings. The Basin and Range faults are a fairly complex set of faults that down drop the units to the west. These faults offset the basal strata of the alluvium. The caldera setting for the Round Mountain deposit is fairly well documented by drilling and mine geologic mapping. The deposit sits above a steeply dipping contact between the Paleozoic and granitic "basement" rocks and the overlying volcanic units. The gold deposit coincides with the edge of the volcanic depression. Core holes have penetrated more3,000 feet of tuff within the inferred caldera. Although the known extent of the caldera is small, most of the caldera is concealed by thick, valley fill to the west in Big Smoky Valley. Hydrothermal alteration ranges from propylitic, to argillic, to quartz-sericite, to quartz-adularia, to silicification, and coarse-gold-bearing quartz veins. Coarse gold is locally present with some "nuggets" of 1 to >100 ounces. The style and type of alteration varies with the rock type. Alteration in the densely welded rhyolite tuff is dominated by quartz-adularia veinlets with erratic gold mineralization; in the non-welded, pumice-rich rhyolite tuff mineralization is more disseminated and accompanied by widespread hydrothermal alteration. Mineralization in the Paleozoic rocks is generally restricted to fracture zones with silicification. These metasedimentary rocks are also one of the significant ore hosts. Mineralization and alteration extends into the Stebbins Hill unit as structurally controlled, silicified and argillized breccia zones. The Stebbins Hill unit probably represents the moat-fill sediments for the Round Mountain caldera A sequence of water-laid tuff, tuffaceous sandstone, conglomerate, and thinly laminated siltstone overlies the orebody.

Comment (Identification): This record includes data MRDS record #M321740 which should be deleted and this record includes all material from MRDS record #W002891 together with additional new material.

Comment (Location): The Round Mountain Gold Mine is located in Big Smoky Valley on the western margin of the Toquima Range. It was initially on the southwest side of Round Mountain peak, (now gone. ). UTM is to the main large open-pit mined area.

Comment (Workings): The Round Mountain Mine has been developed by numerous old underground mines as well as a modern open pit which has obliterated some of the older workings. Historic underground workings include the 1200-foot 20- degree inclined shaft, the Gordon shaft, Placer Vein shaft, No. 2 shaft, Fairview shaft and three adits. A pit expansion was initiated in November 2005.

Comment (Development): The Round Mountain deposits were discovered in 1906 by ranchers John Stebbins and Frank Dixon when coarse-gold-bearing quartz veins were found on the flanks of Round Mountain on claims owned by Lewis D. Gordon. Initial mining operations uncovered gold-bearing veins of spectacular richness, and within a few days of discovery, Gordon sold his controlling interest for some $87,000. From this sale emerged the Round Mountain Mining Co., predecessor of Nevada Porphyry Gold Mines, Inc., the latter destined to become the major property owner in the area. Underground vein mining continued sporadically into the early 1930s. In response to the increase in the price of gold from $20.67 per ounce to $35.00 per ounce, the A.O. Smith Company conducted a very detailed underground sampling program in 1936-37 at a cost of approximately $350,000. The purpose was to evaluate the open-pit potential of the property. The program resulted in some 27,000 fire assays performed on approximately 10,000 samples, mainly meticulously cut channel samples. Intermittent placer operations were carried out for a number of years, and in the 1940s and 1950s, Round Mountain Gold Dredging Co. worked the placers under a lease From Nevada Porphyry Gold Mine. The last placer operations terminated in 1959. In September 1967, Elwood Dietrich obtained a purchase option on the 11,000 acres of mineral rights held at Round Mountain by Nevada Porphyry Gold Mines. In April 1968, Dietrich conveyed his option to Ordich Gold Reserves Company. Copper Range Exploration Company (CRX) reached a purchase option agreement with Ordich effective June 1, 1970. Initial work concentrated on development of the gold placers. In mid-1972, the previously small program to evaluate the bedrock deposits was enlarged and accelerated. Acquisition and re-evaluation of the A.O. Smith Company sampling data showed reserves of 13.2 million tons/0.05 opt gold at a 0.0285 opt gold cutoff and having a 0.2:1 stripping ratio. In November 1972, CRX decided to exercise its option to acquire the ordich-nevada porphyry properties and to proceed with a 1973 program directed toward further evaluation of the bedrock deposits and of heap leaching technology. Pilot heap leaching tests were completed by mid-summer 1973, with favorable results. In December 1973, Smoky Valley Mining Company (a partnership of CRX, Felmont Oil Co., and Case, Pomeroy and Co.) elected to develop the property based on reserve estimates 12 million tons grading 0.062 opt gold and 0.07 opt silver at a cutoff grade of 0.02 opt gold and with a strip ratio of 1.2:1. The Round Mountain Mine was the first major gold mine in North America to be established on the basis of heap leaching as the principal mode of ore processing. Production began in 1977. A deeper disseminated ore zone was subsequently discovered and by 1981 had increased the proven and probable ore reserves to 195 million tons averaging 0.043 opt gold. Homestake Mining gained a 25% interest in Smoky Valley Mining Company by purchase of Felmont Oil Company. In January 1985, Echo Bay Mining acquired the assets of CRX, including 50% interest in Smoky Valley Mining Company with Echo Bay as the controlling partner. Since 1997, development drilling has continued and the reserve base has been significantly expanded and refined. As a result, the total mining rate (ore and waste) increased in a step-wise fashion from 5,450 tonnes per day in 1976 to an average of 275,050 tonnes per day in 1999. The production rate for 2002 averaged 255,825 tonnes per day. The decision to construct a mill to process sulfide ores resulted in a significant increase in reportable reserves in the early 1990's. In December 2001 Barrick Gold Corporation completed a merger with Homestake Mining Company thereby acquiring the Homestake interest in the mine.

Comment (Development): In 2002 Round Mountain Gold Corp. completed a second phase exploration drill program on its Gold Hill property during the second quarter of 2002. The program focused on shallow mineralization to assess the economics of a small starter pit. In 2006, the mine is owned by Kinross Gold Corp. (50%) and Barrick Gold Corp. (50%) and is operated by Round Mountain Gold Corp. a wholly owned subsidiary of Kinross.

Comment (Economic Factors): Historic recorded production from 1906 through 1969 was 346,376 ounces of gold and 362,355 ounces of silver, but actual unreported production was probably significantly higher. Total Round Mountain gold production from 1977 through 2004 is about 9.1 million ounces of gold and 6.8 million ounces of silver. (This figure includes a small amount of production from the Manhattan Mine in 1990). In 2004, total Round Mountain annual production was 762,966 ounces of gold and 773,950 ouncs of silver. Round Mountain reserves in 2004 were reported as 433,400,000 tons of ore grading 0.018 opt gold proven and probable reserves plus a mineral resource of 64,000,000 tons of material grading 0.015 opt gold. Total Round Mountain gold production through 2006 exceeds 10 million ounces. End-of-year 2005 reserves for Round Mountain were 3.9 million ounces of contained gold. Gold production is expected to continue through 2015. Total production from the Round Mountain deposit will be approximately 13 million ounces of gold for the period 1906 to 2015. Round Mountain is one of the giant gold deposits of the world. The total metal content of the system was approximately 20 million ounces of gold.

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References

Reference (Deposit): GSN Precious Metals Symposium, 1987, Fieldtrip Guidebook, p. 130; Technical Volume, p. 375.

Reference (Deposit): Mining Journal, Montagu Mining Finance, Mining Database, 8/10/91.

Reference (Deposit): Tingley, J.V., and Berger, B.R., 1985, Lode-gold deposits of Round Mountain, Nevada: Nevada Bureau of Mines and Geology Bulletin 100, 62 p.

Reference (Deposit): Cavender, W.S., and Purdy, C.P., 1985, The Making of the Round Mountain Mine, in Hollister, V.F., Ed., Discoveries of Epithermal Precious Metal Deposits, Society of Mining Engineers of AIME, New York, p. 101-104.

Reference (Deposit): Mills, B.A., 1985, Geology of the Round Mountain Gold Deposit: Nye County, Nevada, in Hollister, V.F., Ed., Discoveries of Epithermal Precious Metal Deposits, Society of Mining Engineers of AIME, New York, p. 104-114.

Reference (Deposit): Wall Street Journal, 1982, January 5, 1982, "Louisiana Land Boosts Estimates of Gold Reserves."

Reference (Deposit): Nevada Bureau of Mines and Geology MI-1987-2004.

Reference (Deposit): Sander, M., and Einaudi, M., 1987, The Round Mountain Gold-Silver Mine, Nye County, Nevada, in Johnson, J., Ed., Bulk Mineable Precious Metal Deposits-Guidebook for Field Trips, the Geological Society of Nevada, Reno, p. 130-135.

Reference (Deposit): Argall, G.O., 1985, Heap Leaching Smoky Valley Gold, Engineering and Mining Journal, vol. 186, no. 12, p. 18-23.

Reference (Deposit): Sander, M., 1988, Geologic setting and the relation of epithermal gold-silver mineralization to wall rock alteration at the Round Mountain Mine, Nye County, Nevada, in Schafer, R., Et Al, Eds., Bulk Mineable Precious Metal Deposits of the Western United States, the Geological Society of Nevada, Reno, p. 375-416.

Reference (Deposit): Berger, B.R., Tingley, J.V., Filipek, L.H., and Neighbor, J., Processes controlling trace-element patterns in hot springs-related gold-silver deposits in late Oligocene volcanic rocks, Round Mountain, Nevada: unpublished report, Nevada Bureau of Mines and Geology Files.

Reference (Deposit): Skillings, D.N., Jr., Skillings Mining Review, March 3, 1979, p. 8-17.

Reference (Deposit): Silberman, M.L., Shawe, D.R., Koski, R.A., and Goddard, B.B., 1975, K-Ar ages of mineralization at Round Mountain and Manhattan, Nye County, Nevada: Isochron West, vol. no. 13, p. 1-2.

Reference (Deposit): Ferguson, H.G., and Cathcart, S.H., 1954, Geology of the Round Mountain Quad., Nevada: U.S. Geological Survey Geological Quadrangle Map Gq-40.

Reference (Deposit): Koschmann, A.H., and Bergendahl, M.H., 1968, Principal Gold Producing Districts of the United States: U.S. Geological Survey Professional Paper 610, p. 193-194.

Reference (Deposit): Echo Bay Mines Ltd., 1988, Annual Report Form 10-K For 1987.

Reference (Deposit): Echo Bay Mines 1993 Annual Report

Reference (Deposit): Nevada Dept. of Minerals, 1994

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): David L. Emmons, Kinross Gold Company, 2006, Geology of the Round Mountain Gold Deposit, Nye County, Nevada; GSN meeting presentation - October, 2006, abstract.

Reference (Deposit): Ransome, F.L., 1909, Round Mountain: U.S. Geological Survey Bulletin 380, p. 44-47.

Reference (Deposit): Kleinhampl, F.J., and Ziony, J.I.,19854, Mineral Resources of Northern Nye Co.: Nevada Bureau of Mines and Geology, Bulletin 99b.

Reference (Deposit): Ferguson, H.G., 1921, Round Mountain District: U.S. Geological Survey Bulletin 725-I, p. 383-406.

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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.