Moly-Tonopah Mine, Potosi Mining District, Osgood Mountains, Humboldt County, Nevada, USAi

Regional Level Types
Moly-Tonopah Mine	Mine
Potosi Mining District	Mining District
Osgood Mountains	Mountain Range
Humboldt County	County
Nevada	State
USA	Country

Structure: Reg.Struct: Getchell Fault Folds, N-Trending Faults

Alteration: Silication; Silicification; Bleaching And Marbleization

Deposit: Scheelite occurs in a tactite zone about 1000 ft long along E side of osgood granodiorite igneous contact is generally conformable with sedimentary beds, and both strike nw, dip 30-45 ne. Tactite extends down-dip in tabular bodies continuous to the 650 level that is 300 ft below surface. Ore shoots and thicker tactite appear to have formed at rolls and indentations in the contact. At depth, beneath the outcrop, the contact dips east and then reverses to a west dip, then again reverses to dip east. Where the western dip cross cuts the limestone, thick sections of tactite occur. Tactite at this mine is banded, fine-grained, and contains more sulfide than most other deposits in the district. Best ore is composed mainly of fine-grained garnet, epidote and quartz, with large clots of pyrite, pyrrhotite and molybdenite, and scheelite. Away from the contact zone, up section to the east, tactite gives way to silicated limestone interbedded with calc-silicate hornfels, then to bleached and marbleized limestone.

Deposit type: W skarn

Development: This is probably the jack mine mentioned by hess and larson in 1921 As being prospected for cu and mo. The moly-tonopah name was derived from 2 names applied to separate areas of the deposit; the moly workings are on the SE side of the deposit, in the footwall of the getchell south pit gold mine, and are among the oldest in the district, dating back to about 1915, when it was known As the jacks mine. The tonopah name was applied to the north end of the deposit where a small open pit was started about 1943. Because of low-grade and presence of molybdenum, tungsten production from the deposit was low. In 1950-51 and again in 1955-56, the getchell mine inc. Mined about 43000 tons of ore that averaged about 0.29% wo3. Most of this ore was mined from the open pit. Property was inactive at time of examination in 1984, but had been extensively drilled in 1975-1976, at which time a potential 1 to 1.5 million tons of 0.4% wo3 ore was determined for the moly-tonopah area.

Rock formation(s): Osgood Mountains Stock
Preble


Ore(s): Contact Of Granodiorite With Calcareous Sediments

Other Databases

Link to USGS MRDS:	10104129

References