Western Hog Ranch Mine, Washoe County, Nevada, USAi

Regional Level Types
Western Hog Ranch Mine	Mine
Washoe County	County
Nevada	State
USA	Country

Structure: Basin/Range Structural Province; Possible Collapse Caldera Or Failed Caldera System Possible Major Ring-Fracture System - Cottonwood Creek Volcanic Center.

Alteration: Hydrothermal: Silicification, Opalization, Kaolinization (All Pervasive)

Commodity: Gold occurs As finely disseminated flecks, and in some places, is associated with pyrite.

Deposit: Gold mineralization is related both spatially and temporally to peralkaline silicic volcanism and with a probable ring-fracture system. Opalitic veining. This record is an updated version including duplicate information from m232557, w700443, and w700584, which have been deleted.

Deposit type: Hot-spring Au-Ag

Development: Expl.com: the area underwent exploration for uranium prior to the gold discovery. Staked about 1980, optioned by noranda about 1984, who, with ferret exploration did extensive drilling and exploration on it. In aug. 1984, geomex owned a 63% working interest in hog ranch and was doing more drilling and metallurgical testing on it. Imperial metals had acquired an interest in hog ranch by feb, 1986. Western goldfields and ferret exploration acquired the property and were seeking operation permits in march 1986 which were granted with operations commencing in april, 1986. In august 1986, orofino resources acquired a 10% interest in it with other partners western goldfields, 50% ; geomex minerals, 30%; and montagu mining investments, 10%. Leach pads were being filled in sept, 1986. In april 1987, royal resources corp bought up all montagu's stock including its 10% hog ranch interest. First pour was in late 1986 with expected production of 50,000 oz au/year. Western goldfields increased its interest to 65%. Initial mining was mostly at the krista pit with continued work to develop ore south of krista. Feasibility study for bell springs deposit 4 miles s W of krista pit was underway with plans to start development on it in 1988. ; total$: 7.7 ; econ.com: total project capital cost of $7.7 million. In 1987, total unit cost per ton of ore was $10.76 and direct operating cost per ounce of Au was $214. Average strip ratio is 1.1:1. The mine produces dore bars containing 95% au. Three grade categories are used: ore ( 0.025 opt au), run of mine material (0.01 and < 0.025 opt au), and waste (<0.01 opt au). Ore is crushed to minus 1.5 in. In two stages and agglomerated with cement, lime, and cyanide solution prior to stacking on the heap leach pad. Run of mine material is taken to the pad and is stacked on top of exhausted heaps for leaching. Estimated Au recovery for this material is 40%. It pays for its mining and reagent costs, and contributes about $1 per ton to revenue.

Geology: The hog ranch property is located in the transitional zone between the columbia plateau physiographic province to the north, and the basin and range province to the south. The region exhibits characteristics of both provinces. The krista pit exhibits a typical disseminated hot-spring Au-ag deposit which has strong structural control. Gold values are largely found, and are highest in the more intensely silicified (chalcedony) rocks. Probable near surface mineralization. Slightly anomalous radioactivity has been reported from petrified wood in late miocene sedimentary rocks. Uranium occurrences along hog ranch creek which extend for several miles; +/-3000 m.

Ore(s): Fractures

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Link to USGS MRDS:	10047581

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