Structure: Walker Lane structural zone

Alteration: Vikre and McKee have identified five distinct hydrothermal mineral alteration assemblages affecting the host andesite in the Como District. Some of these are spatially restricted to vein selvages and others are more widespread. Mixed clay alteration assemblages indicate periodic changes from acid leaching to neutral conditions during gold-silver deposition. Alteration minerals proesent are: quartz, diaspore, sericite, kaolinite,dickite, halloysite, pyrophyllite, pyrite, montmorillonite, and alunite.

Commodity: Commodity Info: silver/gold ratio of 25/1 Ore Materials: free gold, pyrite, silver chloride,tetrahedrite, copper-lead-zinc minerals Gangue Materials: quartz, pyrite, sericite, clay minerals, alunite

Deposit: Historically, mineralization in the district is contained in quartz veins of the Buckeye-Como vein system. Underground mine records show that the Buckeye-Como vein was mined along a continuous zone 720 feet long. Veins were 10-50 feet wide with up to 4 feet of soft crumbly quartz on the hanging wall and were developed along strike for more than 1600 feet. Ore is oxidized down to 250 level, below which veins were barren. Quartz vein is made up of hard white or slightly bluish-tinged quartz, banded in some places, with later clear quartz crystals filling cavities. The Elgin vein parallels the Como vein about a1000 feet to the south. Although the Elgin Vein has had minor recorded production, assays along the surface of the veil and drilling encountered high-grade gold-silver mineralization along an untested strike length of 3,000 feet. Additionally, Anglo?s drilling discovered a "new" high grade (0.45 opt over 10' within a mineralized zone that is 40-70' in thickness) vein system. RSM plans to test the western extension of the Elgin vein where it plunges under valley cover. Similarly encouraging assay results were obtained for mineralization along the Como vein, Palmyra vein/stockwork, and the Hully-Logan vein areas which offer targets for gold-silver resources that have not been drill tested.

Deposit type: Epithermal vein, Comstock

Development: In 2002, Royal Standard Minerals Inc. acquired the Como gold-silver property consisting of 47 (now 60) unpatented lode claims and five patented claims in the main historic Como District, which produced between the 1860s and 1930s. Since the 1960s several large companies, including St. Joe American, Amoco, Meridian Gold, Amax Gold Inc., and Anglo Gold Corp., have explored the property. Amax identified a low grade open pit resource, based on 46 holes. Anglo released the property in 2001 after drilling eight holes and completing considerable surface geologic mapping and geochemical sampling. Anglo's drilling program discovered a quot;new" high-grade vein system (0.45 opt over 10 feet within a mineralized zone that is 40 to 70 feet thick). Royal Standard began follow up work based upon the previous exploration results and in February 2004 announced the completion of the evaluation of its Como Gold-Silver Project. Past work has identified two bulk-mineable gold-silver targets requiring further work. Anglo Gold conducted perhaps the most intriguing work on the property in 2000, looking for a multi-million ounce deposit. Although they released the property in 2001, their drilling identified a high-grade vein system that with values of 0.45 opt over a 10-foot width with a thickness ranging from 40 to 70 feet. Surface rock chip samples on this vein have returned values up to 0.417 opt gold.

Geology: Quartz vein textures and inclusions indicate a gold-depositing boiling environment.

Ore(s): Shear zones

Fossils

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Other Databases

Link to USGS MRDS:	10310425

Mindat Articles

The Como mining district, Lyon County, Nevada by Kyle Beucke
The Como mining district, Lyon County, Nevada: Part 2 by Kyle Beucke

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References