Wind Mountain Mine, San Emidio Mining District, Washoe County, Nevada, USAi

Regional Level Types
Wind Mountain Mine	Mine
San Emidio Mining District	Mining District
Washoe County	County
Nevada	State
USA	Country

Structure: See Comments

Alteration: See Comments

Commodity: Ag:au ratio approx. 15:1 metallurgical testing indicates gold occurs on microfracture surfaces and is not encapsulated by silica, suggesting gold deposition postdates most of the silicification. The clay used to construct heap leach pads, etc. Was mined on site from zones of argillization. The clay may have potential for further development.

Deposit: This is an updated record including data from re00016 which has been deleted. ; info.src : 1 pub lit; 2 unpub rept; 3 field observ deposit formed in a near surface environment from a hot spring type geothermal system. Individual beds range from 5 cm to 1 m thick. Several small subaqueous basalt or basaltic andesite flows are interbedded with siltstone and shaley lake beds. 2-3 sq km of pliocene tuffaceous and volcaniclastic sedimentary rocks are argillized and silicified. A small hill on the property is capped by stongly silicified material, probably subaqueous spring sinter As well As some lenses of light gray chalcedony. Hydrothermal stockwork breccias occur at several localities, the largest is a zone 40 m wide and extends 600 m along a n20 W normal fault and the lake range fault. Three major gold mineralized zones have been defined by drilling; the wind mountain orebody and the currently subeconomic northwind and breeze gold zones.

Deposit type: Hot-spring Au-Ag

Development: The earliest prospectors were probably prehistoric indians who collected silica chips for toolmaking. The first mining claims were staked in the area around 1900. Old prospect pits indicate native sulfur, cinnabar, and opal were of principal interest. Minor quantities of Au and Ag were discovered in the 1930's and several adits and prospects were excavated in a small area 1 km sse of wind mountain. Prospecting activities for sulfur, cinnabar, gold, silver, and montmorillonite continued through the 1970's. In 1979, tmb associates staked the core claim block. Amax exploration, inc., leased the property in 1980 and drilled 10 holes. Holes a-3 and a-4 intersected a zone 76 meters thick that averaged 0.79 gpt Au and 25 gpt ag. Amax relinquished the property in 1982 due to the overall lo W gold values and apparent small size of the mineralized area. Santa Fe pacific mining co. And chevron resources co. Held parts of the property from 1983 to 1986, and drilled 31 and 7 holes, respectively. No significant NE W mineralized zones were encountered and the property was returned to the owners. Amax reevaluated the property in 1986 and reacquired the property in 1987. 28 widely spaced reverse circulation holes and 4 core holes were drilled in 1987. Holes a-28 and a-31, spaced 122 meters apart on the top of the mountain, intersected 78 meters of 0.99 gpt Au and 16.6 gpt Ag and 78 meters of 0.93 gpt Au and 21.5 gpt ag, respectively. Each of these holes contained 1.5 meter thick intercepts of 161 gpt Au and 44.5 gpt au, respectively. 105 additional holes were drilled in 1988. An orebody containing 13.7 million metric tons grading 0.72 gpt Au and 11.4 gpt Ag was defined by june 1988, and the decision to develop the mine was made. In 1989, 188 drill holes totalling 20,591 meters were completed. Mine construction was delayed to january 1989, pending completion of an archeological mitigation survey. ; econ.com: cash operating costs were $265/oz Au in 1989 and $197/oz Au in 1990. Total operating costs (including depreciation and amortization) were $372/oz Au in 1989 and $310/oz Au in 1990. The precipitate product from heap leaching is transported to the sleeper mine for processing into dore.

Geology: The wind mountain mine is located at the NE edge of the san emidio known geothermal resource area. Temperatures exceeding 100 degrees c have been encountered over an area of 26 square km. Ormat energy systems, inc. Operates a geothermal power plant 7 km south of the mine. Native sulfur and cinnabar occur in a 200 ft. Wide strongly argillized zone in quaternary gravels for 7 km along the range front south of wind mountain.

Rock formation(s): Pyramid Sequence
Truckee Formation


Ore(s): The Range Front Fault System At The Nw Side Of The Lake Range And Dilation Of Faults Associated With A Gradual Collapse Centered About 800 Meters West Of Wind Mountain Were Responsible For Localizing The Gold-Bearing Hydrothermal Fluids.

Other Databases

Link to USGS MRDS:	10047586
Link to USGS MRDS:	10310384

Other Regions, Features and Areas containing this locality

References