Structure: Roberts Mountains Thrust

Alteration: Sericitic, Argillic

Commodity: Arsenic and gold were the most effective surface geochemical indicators.

Deposit: Nodular turquoise forms lenses and seams along quartz veins in altered dikes and along faults. Blue star Au mineralization is partly hosted by upper plate rocks, and is accompanied by abundant cu mineralization with little carbonaceous material. In blue star upper pit, n W of the blue star mine, disseminated Au mineralization occurs along a steep n20e fault, with highest grade ore localized at intersection of an older e- W fault and a younger n-s fault. First production year: 1929 (turquoise); 1960 (au) discovery year: 1929 (turquoise); 1959 (au)

Deposit type: Carbonate-hosted Au-Ag

Development: Small bodies of gem-grade turquoise were discovered and developed in 1929 at the number eight mine along the ridge forming the west edge of little boulder basin, about 3/4 mile east of blue star. Total turquoise production since 1929 is estimated at $1,500,000. Au was discovered in 1959 at the number eight mine along the roberts mountains thrust. A 100 ton cyanide mill was erected on the property in 1960 and was operated in a small way until 1962. Kerr-mcgee oil industries purchased the property in 1964. Newmont acquired the blue star turquoise property in 1968. Exploration drilling identified reserves of 1.6 million tons/0.12 opt Au in three orebodies. Open pit mining began in 1974 at blue star. ; econ.com: there is a 10:1 ratio of heap leach ore to mill ore at blue star. 1654 holes totalling 850,000 ft. Have been drilled As of april, 1990 to define orebodies at blue star and the nearby genesis mines.

Geology: Copper mineralization appears to predate the gold deposition. Turquoise was concentrated along quartz veins in alterred dikes and along faults cutting the thinly bedded shale, siltstone, and chert. The turquoise was nodular, forming lesnes and seams. 10% was gem quality (morrissey 1968). Gold has been recognized As discrete grains 1 to 13 microns, at the borders of detritalquartz grains and within quartz overgrowth on detrital grains. Gold in mineralized dikes was associated with sericite. A large portion must be less than .5 microns and unrecognized. Vinini formation: most favorable host rocks are sandy siltstones, quartzite sandstones also work well As hosts. The limestones are poor hosts without extensive hydrothermal ground preparation. Dacite porphyry dikes & quartz diorite plub outcrop to the west and north. The diorite was dated As 121 million years. Both are strongly altered with argillic and sericitic assemblages recognized. Unalterred post-mineralization rhyolite porphyry was encountered in drill holes in the mine area..

Rock formation(s): Vinini Formation;Vinini Formation;Vinini Formation

Ore(s): Orebodies Are Located On The West Limb Of A North-Trending Anticlinal Structure Which Is Cut By E-, Ne-, And Nw-Trending Normal Faults. Orebodies Are Restricted To Strongly Fractured, Near E-W High Angle Faults And A Ne-Trending Diike Swarm. South And East Orebodies Lie Immediately Below The Roberts Mountains Thrust, While The North Orebody Lies Directly Above The Thrust. Igneous Dikes Host A Minor Amount Of Ore.

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Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

16 valid minerals.

Rock Types Recorded

Note: data is currently VERY limited. Please bear with us while we work towards adding this information!

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Alphabetical List Tree Diagram

ⓘ Quartzite

ⓘ Rhyolite