Horse Canyon prospect, Lewis Mining District, Lander County, Nevada, USAi

Regional Level Types
Horse Canyon prospect	Prospect
Lewis Mining District	Mining District
Lander County	County
Nevada	State
USA	Country

Sec 4 T29N R45E. Gold
Structure: Roberts Mountains Thrust; Cortez Window high angle faulting; fractures; folding

Alteration: silicification, bleaching, clay alteration

Commodity: Ore Materials: gold, barite, sulfides Gangue Materials: quartz, clay, jarosite, iron oxides, pyrite

Deposit: Fine-grained gold is disseminated in carbonaceous shale in the upper plate of the Roberts Mountain thrust. Ore is localized by the Roberts Mountains Thrust plate contact and by north-striking high angle structures. Ore zone is characterized by jasperoid breccia. The surface expression of the deposit was a bouldery resistant rib of jasperoid trending northwest along most of area covered by drill roads prior to mining. .

Deposit type: Sediment-hosted Au

Development: The Horse Canyon deposit was discovered about 1982 and open pit gold mining commenced in 1983, employing 106 workers. Annual recovery of 40,000 ounces of gold was projected. The mine produced until 1985 and again 1988-1993. With the upswing in gold prices, Cortez Gold Mines began re-exploring near the old Horse Canyon Mine area and in late November 2002, five drill rigs were mobilized in the area. With the 2002 discovery of the Pediment and Cortez Hills deposits, CJV continued exploration in what they call the Horse Canyon/ Cortez Unified Exploration Program for which and Environmental Assessment was filed in Sept., 2004. The EA described a proposed Phase I Exploration Program that would involve widespread exploration drilling to advance/test target areas. It will include approximately 150 drill sites followed by follow-up drilling of another 100-200 drill sites.

Geology: The deposit area was visited by NBMG geologists in 1982 before it was mined. Along the southeast drill roads, the most conspicuous feature was a Vinini-hosted jasperoid breccia forming a resistant NW-striking rib above the drill roads. Jasperoid is highly silicified, fractured, and iron stained along the fractures. Bedding is preserved in the jasperoid in places and dips southeast. Below the jasperoid breccia are thin contorted beds of black carbonaceous shales. In one area the southeast -dipping shales are cut by an altered igneous dike, mostly altered to clays. The surrounding shales have been bleached. A sample was taken here, of black siliceous shale and cherty shale drill cuttings. To the northwest in probable future pit area, the resistant rib of Vinini jasperoid breccia is still present. Below the breccia are thin bedded siliceous sediments. A large boulder of breccia found on the road was cut by a small breccia vein containing a clast of quartz-eye porphyry. However, the most notable occurrence was of abundant euhedral jarosite crystals developed in the open fractures of the jasperoid (sampled). Some barite vein and gangue was also noted in this area. Another sample consists of drill cuttings of dark gray calcareous shales with fine disseminated sulfides.

Ore(s): Ore is localized by the Roberts Mountains Thrust plate contact and by north-striking high angle structures.

Other Databases

Link to USGS MRDS:	10310318

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References