Gold. Sec 27 T31N R43E
Structure: Roberts Mountains Thrust; Dewitt Thrust N-S Striking, Steeply East Dipping Faults

Alteration: Prograde Skarn, Retrograde Skarn. See Geology Comments.

Commodity: The textural relationship of Au to other minerals in the ore zones had not been recognized in microscopic work completed through 1984. However, statistical evaluation of drill hole assays suggests that Au is closely associated with pyrrhotite and pyrite. Free au, generally less than 0.05 mm diameter, was recovered during milling of ore from the tomboy-minnie deposits. Ag mineralization correlates closely with the occurrence of galena. Anomalous au, Ag values at or near surface are spatially associated with the orebodies. This zone is surrounded by a halo of anomalous zn, pb values.

Deposit: Refer also to minnie mine (record #231355).

Deposit type: Skarn Cu

Development: The property was located by lyman sands and william gibson about 1900. Work was sporadic with no production until 1926 when sands erected a 35 tpd denver quartz mill SE of the mine. The mill operated for 7 months, treating 4000 tons of ore. The property was then acquired by shovelin, whose lessees shipped some ore to utah smelters through 1938. In 1948, a road was constructed to the copper canyon mining co. Mill a mile to the north, and 5723 tons of ore were trucked there from the tomboy mine for processing. The heads averaged 0.22 opt Au and the recovery was 0.18 opt au. Duval corp. (no W battle mountain gold co.) acquired the property in 1968. Duval mined the tomboy-minnie deposits 1978-1982.

Geology: Alteration comments: prograde skarn, retrograde skarn. Shale and siltstone of the harmony formation were converted to brown biotite hornfels during emplacement of the granodiorite of copper canyon, while sandstones sho W strong effects of recrystallization and silicification wherein the fine grained matrix was altered to clay minerals, white mica, and secondary quartz. Thermal effects resulted in the calcareous basal conglomerate of the battle formation being converted to a quartz+diopside+epidote hornfels assemblage with sparse garnet replacing some limestone clasts. Introduction of free gold and pyrite occurred penecontemporaneously with replacement of the early diopside assemblage by actinolite, tremolite, and chlorite. Geology comments: pre-1965 workings were in conglomerate in the lower part of the battle formation just above the contact with the harmony formation. The orebody was localized in and near fractures that cut the conglomerate and in replacement zones within the conglomerate. Mineralized fractures continue downward into the harmony formation, but there is noticeably less extensive mineralization adjacent to them there. Sulfide content in ore zones in the basal conglomerate of the battle formation ranges 10-50 volume percent and consists mostly of pyrrhotite and pyrite. Local pod-like replacement bodies of Fe-rich sphalerite and galena have also been recognized. Other sulfides in decreasing abundance include marcasite (replacing pyrrhotite), chalcopyrite, and arsenopyrite.

Rock formation(s): Harmony Formation;Copper Canyon Stock
Battle Formation

Ore(s): Replacement Type Mineralization Of The Tomboy-Minnie Deposits Is Generally Confined To The 30 M Thick Calcareous Basal Conglomerate Of The Battle Formation.

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Mineral List

12 valid minerals.

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