Gold Quarry Mine, Maggie Creek Mining Subdistrict, Carlin Trend, Eureka County, Nevada, USAi

Regional Level Types
Gold Quarry Mine	Open-Cast Mine
Maggie Creek Mining Subdistrict	Subdistrict
Carlin Trend	Group of Mines
Eureka County	County
Nevada	State
USA	Country

A former Au-Ag-As-Sb-Hg-Tl-Ba-Pb-Zn-Cu-Mn-Ni occurrence/mine located in sec. 35, T34N, R51E, MDM, 7 miles (ca. 11 km) NW of Carlin, on land of mixed ownership (located claim; private lease; private). Discovered in 1925 by A. Berning. Produced from 1936 until 2004. Owned and operated by the Newmont Gold Co. (Newmont Mining Corp.) P.O. Box 979, Carlin, Nevada 89822 (1988). MRDS database stated accuracy for this location is 10 meters.

HISTORY: The first claims were staked in 1925 by A. Berning, who leased the property to Cuba Consolidated Mines Company. In 1936, Cuba Consolidated shipped 60 tons of ore averaging 0.417 ore percent (OPT) Au, 0.882 OPT Ag. Newmont Corp. acquired the property in 1962 and conducted a drilling program in 1963-1964 in the vicinity of what is now the northern limit of the Gold Quarry. Drilling was centered SW of the jasperoid outcrop from which the 60 tons of ore were mined. Further drilling until 1970 delineated 340,000 tons/0.12 OPT. The lease agreement was discontinued in 1970 due to low Au prices and discouraging metallurgical tests. The property was acquired by Roy Ash and Charles Thornton for $8,000.00. After XRF-XRD studies of Gold Quarry drill cuttings suggested possible open ends of mineralization, the claims were reacquired in 1972. After 1979, Exploration drilling continued East of the Maggie Creek orebody and significant Au intercepts were encountered. Between 1979 and 1983, 550 conventional circulation holes were drilled on 100-foot centers to an average depth of 600 feet (ca. 183 m). Bulk metallurgical test samples of mill-grade and leach-grade material were mined in 1982-1983. Pre-mining began in late 1983. The first Au was poured in August 1985 (total $: 300). The development consists of a 40-foot adit and other scattered open cuts.

The new semi-autogenous mill complex currently (1992) processes more than 28,000 short tons (ca. 25,400 metric tons) per day. In 1989, the Gold Quarry pit was producing 60% of the total material mined and 62% of the Au recovered by Newmont. A total of 300 hourly and salaried people were employed in the Gold Quarry Mine operations group.

MINERALIZATION: Mineralization is a polymetallic deposit (Deposit model code 172; USGS model code 26a; BC deposit profile E03; Deposit model name: Carbonate-hosted Au-Ag deposit; Mark3 model number: 15), hosted in rocks of the Vinini Formation (quartzite, siltstone, carbonate, and chert) plus jasperoid. At the Gold Quarry deposit, in the central Carlin trend, Heitt (1992) reported K/Ar dates ranging from 28 to 27 Ma from supergene alunite veins that crosscut and postdate gold mineralization. The orebody is tabular.

Au is associated with As, Sb, Hg, & Tl. A subordinate association of Ag, Pb, Zn, Cu, & Ni appears to represent earlier mineralizing events. Au grains range <0.1 to 10.0 microns in size and usually occur associated with micro-fractures or disseminated in microcrystalline cherty matrix. Au:Ag ratio ranges from about 2:1 in mill-grade ores to 1:3 in leach-grade ores. Local alteration is silicification and clay. Local rocks include platy limestone and limy siltstone, chert at the base.

LOCAL GEOLOGIC STRUCTURES: Geologic structures include the Roberts Mountains Thrust, Good Hope Fault system, Gold Quarry Fault, Etc. These structures created a pervasive fracture system at the Gold Quarry. Isoclinal folding of bedding is common. Fissures, fractures zones, faulting, and folding all controlled ore deposition. The Less fault, a high-angle NE-striking structure, was an ore-controlling structure in the original Maggie Creek pit.

The deposit is located at the SE corner of the Carlin Window in the Roberts Mountains thrust. The NW-striking Snowbird anticline and Alta anticline have folded host rocks in the pit area.

GEOLOGY OF THE DEPOSIT: Gold Quarry is one of the largest Au deposits in North America. It consists of 2 stacked orebodies: An upper structural stockwork and a lower, stratabound replacement. Overall strike of the main (upper) ore zone is N45E. It is bounded on the W by the Gold Quarry and on the E by the Grey/Challenger fault systems. Mineralization is continuous over 6,000 feet (1.83 km) of strike. Mill-grade ore zones crosscut this trend on a N-S to NW strike. The Deep West orebody is a silica replacement zone at the contact of footwall carbonate rocks and hanging wall siliciclastic rocks. It averages 250 feet (ca. 76 m) in thickness, strikes N20E, dips 30-35SE, and has a known strike length of 2,500 feet (ca. 762 m). The gold grade is double that of the main (upper) ore zone. The Deep West ore zone is the down-dip extension of the Maggie Creek South ore zone.

Gold is present in a gossan in quartzite and chert. Many of the baryte and base metal deposits in the Maggie Creek subdistrict are associated with the Good Hope Fault system (e.g., the Nevada Star Mine, record #M232284). This fault system also appears to link the Gold Quarry and the Tusc deposits. A sense of movement on the Good Hope Fault system has not been established. North of the intersection of the Gold Quarry and Good Hope faults, an entire ridge of silicified Roberts Mountains Formation marks the margin of the Carlin Window. The jasperoid reportedly carries some Au. Gold Quarry and Maggie Creek mines are unusual in that ore is hosted, at least in part, by Paleozoic rocks of the upper plate of the Roberts Mountains thrust.

WORKINGS DATA: Workings include surface openings comprised of open pits. Historic development consisted of a 40-foot (ca. 12 m) adit and other scattered open cuts. The current (1992) operation consisted of an open-pit mine, 2 milling facilities, a leach crushing plant, and 3 leach pads. The dimensions of the ultimate pit will be 1 mile (1.61 km) by 0.75 mile (1.21 km) in size and 1,200 feet (ca. 366 m) in depth. The total material in the ultimate pit is estimated at 576.3 million tons, which reflects a 1.3:1 strip ratio.

PRODUCTION DATA: Early shipped ore averaged 0.417 ounces (ca. 16 g)/ton Au and 0.882 ounces (ca. 33 g)/ton Ag.

Other Databases

Link to USGS MRDS:	10044714
Link to USGS MRDS:	10125143
Link to USGS MRDS:	10310465

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