Tunnel Hill Mine, Velvet Mining District, Pershing County, Nevada, USAi

Regional Level Types
Tunnel Hill Mine	Mine
Velvet Mining District	Mining District
Pershing County	County
Nevada	State
USA	Country

Sec 25 T28N R28E. Diatomite
Deposit: Worked by two open pits; main pit is 1100 x 700 ft. And 50 ft deep. Developed by 60 bulldozer cuts and 42 drill holes ; info.src : 1 pub lit; 2 unpub rept; 3 field observ miocene diatomite unit in small basin completely surrounded by basalt hills. Diatomite dips 15 degrees or less south or east with total exposed stratigraphic thickness of 100 ft. Faults are common (mostly high-angle) with offsets of less than 10 ft. Minor flexures are also present, some caused by soft-bed folding. In the lower part of the sequence, beds of impurities generally 2-12 in. Thick are spaced at 0.5 to 8 ft intervals. Most of these beds are volcanic glass with varied amounts of grit; some also contain diatoms. In the upper part of the diatomite unit, several beds of cross-cutting beds, apparently because of infilling, and one shows cut-and-fill structure into the diatomite. In the s W face, a thin sliver of basalt is down-faulted onto diatomite. Bedding of the diatomite ranges from laminated to thin-bedded. The white, fine-grained diatomite consists mostly of melosira. The material is very slightly iron-stained locally and contains a fe W very thin beds rich in dark iron oxides.

Development: Developed by 2 open pits, 60 bulldozer cuts and 42 drill holes. No activity at time of examination in 1984, but mine is intermittently active.

Geology: Three diatomite beds 4 to 55 ft thick interbedded with tuff and sandstone within stratigraphic interval of 150 ft; opal is a minor impurity.

Ore(s): Stratigraphic In Lake Deposits In Basin

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Link to USGS MRDS:	10042439

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References