Black Jack Mine, Imlay Mining District, Pershing County, Nevada, USAi

Regional Level Types
Black Jack Mine	Mine
Imlay Mining District	Mining District
Pershing County	County
Nevada	State
USA	Country

Sec 25 T31N R33E
Structure: Humboldt Range ; Reg.Trends: North To Northeast Low-Angle Shears At Shale-Limestone Contact.

Alteration: Silicification

Tectonics: Basin And Range

Deposit: Concentration of cinnabar primarily controlled by nearly flat contact between shale and overlying massive limestone. Cinnabar occurs in a thin-bedded limestone layer in the upper member of the prida fm. The cinnabar occurs in recrystallized gray limestone with white calcite veinlets. The cinnabar occurs along fractures and disseminated along bedding planes As small crystals up to 0.5 mm. The mineralized zone strikes n40-50 W and dips 30 ne. The mineralized limestone is enveloped by brecciated and silicified limestone (jasperiod) with lenses of gossan. There is no visible cinnabar in the jasperiod or gossan. Discovered in 1906. Production years 1913 and 1940-41. Workings consist of about 1,000 feet of adits and interconnecting stopes from which all of the ore was mined. Rocks of the area consist of limestone with thin black shale interbeds part of the triassic star peak formation. The property is the oldest known cinnabar deposit of importance in nevada. ; info.src : 1 pub lit; 2 unpub rept; 3 field observ

Deposit type: Almaden Hg

Development: First staked in 1906 As the ruby claim and is the oldest known cinnabar deposit of consequence in nevada. Operated in 1913 As the ruby mine producing 425 flasks from a 12-pipe retort built in the canyon below the mine. 347 flasks recovered in 1914, but after exhaustion of the rich ore, the property remained idle for over 25 years. In 1939, t. W. Hebbard and h. E. Lufek relocated the property and changed its name to the eldorado mine. In 1941-42, 199 flasks hg were produced from ore hand sorted at the mine site and sledded out in winter to the retort site. Idle in 1943. With higher hg prices, in 195455 the ground was relocated As the black jack and nos. 1-6 claims by briggs and frank noble. A 25 ton gas-fired rotary furnace plant was installed in 1955 by earl simpson, and by 1959, 263 flasks recorded production. In 1961 and 1964 a very few flasks were produced, perhaps by a cleanup. From 1965 to 1969, owners reported mining, screening and milling ore, but the only production recorded was 20 flasks in 1965. Since 1969, some underground and surface work has been done with no production recorded. In 1981, the small screening plant installed high on the hill near the portal of one of the lower adits was still on the property and the remains of the old retort were still at the mill site in the canyon although the rotary furnace had been completely removed. In 1984, several drill roads 2-3 years old and 4 or more rotary drill holes beneath the mercury mine were noted, but no current activity.

Geology: Concentration of cinnabar primarily controlled by nearly flat contact between shale and overlying massive limestone. ; major.units: triassic sedimentary rocks ; geol.desc: triassic limestone and shale intruded by jurassic (?) granite

Ore(s): Shale Beneath Limestone

Other Databases

Link to USGS MRDS:	10040305

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References