Pine Nut Molybdenum Prospect (Pine Nut deposit; Gardnerville Mine Area; Alpine Claim; Cosmos Claim; Extension Claim; Owl Claim; Ramona Claim; Scheelite Claim; Tungstate Claim), Gardnerville Mining District, Pine Nut Mountains, Douglas County, Nevada, USAi

Regional Level Types
Pine Nut Molybdenum Prospect (Pine Nut deposit; Gardnerville Mine Area; Alpine Claim; Cosmos Claim; Extension Claim; Owl Claim; Ramona Claim; Scheelite Claim; Tungstate Claim)	- not defined -
Gardnerville Mining District	Mining District
Pine Nut Mountains	Mountain Range
Douglas County	County
Nevada	State
USA	Country

Structure: Rocks in the district have been affected by a broad NNE-trending anticline, and by two sets of faults, one striking NNE and one striking NW to NNW, more prominent in the prospect area. Rocks in the district have been affected by a broad NNE-trending anticline, and by two sets of faults, one striking NNE and one striking NW to NNW, more prominent in the prospect area.

Alteration: Host rocks have been silicified, sericitized, and K-feldspar altered.

Tectonics: Tertiary to Recent Basin and Range type faulting bounds the ranges.

Commodity: Ore Materials: scheelite, powellite, molybdenite, huebnerite Gangue Materials: quartz, pyrite, sericite, calcite, pyrite, limonite, and hematite.

Deposit: At the old Gardnerville Mine, scheelite occurs in skarn that partially replaces a 6-ft thick bed of dolomite. The dolomite strikes NW and dips 45-75 SW with a footwall of at least 20 feet of spotted schist and a hanging wall of schist 10 feet thick. Only part of the host dolomite has been changed to skarn and only part of that skarn contains scheelite. The best tungsten ore ran 1.5 % WO3 and was 2-3 feet wide. No tungsten ore was found below the 200 foot level. Powellite occurs with the scheelite especially in the lower levels. On the 400 level of the old Gardnerville Mine, powellite is abundant and fine-grained molybdenum is common. In the 1960s, a broad zone of molybdenite mineralization was detected by surface geochemical exploration and subsequent diamond drilling encountered significant molybdenum mineralization. Molybdenite occurs in a stockwork of quartz and quartz-pyrite veins accompanied by sericite and quartz-K-feldspar alteration. Huebnerite has been identified in some of the quartz-pyrite veins.

Deposit type: Porphyry Mo, low-F

Development: The Gardnerville mine at the center of the molybdenum prospect, was first operated in 1937 by the Nevada Tungsten Corporation, who built a small gravity mill and produced 723 units of WO3. Rare Metals Corporation acquired the property in 1940 and did some additional development work in an unsuccessful search for more ore. Various owners and lessees operated on the claims from 1951 to 1956, producing more than 12,000 units of WO3. Climax Molybdenum Company, began exploring the property in 1963 for porphyry-type molybdenum mineralization. A broad zone of molybdenite mineralization was detected by surface geochemical exploration, and subsequent diamond drilling encountered significant molybdenum mineralization.

Geology: The rocks exposed in the Gardnerville District are Triassic to Jurassic age metavolcanic and metasedimentary rocks that have been cut by light gray felsic dikes. Small outcrops of biotite-quartz monzonite are found locally and it is probable that a larger mass of Cretaceous granitic rock underlies the metasedimanetary rocks at a shallow depth. Scheelite occurs in thin beds of skarn which have replaced impure limestone and dolomite in the metasedimentary section. In the southern part of the district in the vicinity of the Gardnerville Mine, molybdenite mineralization has been found in a stockwork of quartz veins generally related to the underlying quartz monzonite stock.

Ore(s): The deposit is controlled by lithology where dolomite altered to skarn, and by proximity to a pluton.

Other Databases

Link to USGS MRDS:	10310342

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References