Cimarron Mine, San Antone Mining District, San Antonio Mountains, Nye County, Nevada, USAi

Regional Level Types
Cimarron Mine	Mine
San Antone Mining District	Mining District
San Antonio Mountains	Mountain Range
Nye County	County
Nevada	State
USA	Country

Structure: The Cimarron deposit lies along the northeastern margin of the Walker Lane mineralized structural zone The Cimarron property is situated at the intersection of this northwest-trending regional structure and a northerly-trending belt of productive (+1 Moz) gold deposits .

Alteration: bleaching and argillization of host rocks

Commodity: Ore Materials: native gold Gangue Materials: quartz

Deposit: The Cimarron gold deposit is a low-sulfidation volcanic-hosted, epithermal gold system containing disseminated and quartz-vein stockwork mineralization with locally high grades (>20 g/t gold). At least seven zones of mineralization have been identified; three of these contain a combined resource of at least 50,000 ounces gold and remain open. The three zones cover about 44 acres (.18 sq km), wrapping around the northwest side of an intrusive rhyolite dome. Only a few holes used in the resource calculation exceed a depth of 160m (500ft), and most are within 100m of surface. A number of holes bottom in mineralization. Only 21 additional holes have been drilled in the resource area since 1988, and most of these holes encountered mineralization High-grade gold mineralization occurs within quartz veins, vein stockworks and breccia zones along northwest-trending structures. Mineralization also commonly follows the margins of intrusive flow domes and dikes. High-grade mineralization occurs within an area of at least 2 km strike length and up to 1 km in width. Examples of high-grade (+.25 opt Au, + 8.6 g/t Au) gold values occur in outcrops and underground workings The strongest mineralization in the main resource area occurs where high-angle NW- and N-trending structures intersect a gently-dipping coarse-grained tuff, resulting in stratiform, gently-dipping mineralization within the tuff marginal to the structures.

Deposit type: Epithermal vein, Comstock

Development: The historic Cimarron/San Antonio Mine operated from 1937 to 1940, producing one verified shipment of 9.6 tons of ore containing 13.3 ounces of gold and 47.2 ounces of silver with a gross value of $447.64 (1937). In 1950, Chicago interests leased some of the claims and planned to drive a 400-foot crosscut to the gold-bearing zone, but no significant production resulted. The property was owned by Margaret Booth and Mrs. D.A. Orton in the early 1970s at which time there was still some small-scale underground mining that ceased soon thereafter. Since that time, 6 exploration programs have been conducted in the district. The principal efforts have been by Newmont Mining (1980-1981), Gold Fields (1985), Echo Bay (1987-1988) and Romarco (1995-1997). In 1996, the Cimarron gold property was joint-ventured by Romarco Minerals and Brancote USA, a wholly owned subsidiary of Landore Resources Inc., with operator Romarco holding a 70% interest. That year, Romarco drilled 22 shallow reverse circulation holes at the Cimarron property. Brancote optioned the Cimarron property to Cimarron Mining Corp., a wholly-owned subsidiary of Bullion River Gold Corp in 2004-2005. About 290 holes have been drilled, mostly within the main resource area. Drilling has intersected gold mineralization in each of seven zones in the Cimarron area. A resource of 50,000 ounces in three of these zones was estimated in 1988 using about 190 drill holes and a cutoff grade of 10 feet of .015opt Au (.5 g/t over 3m). The main resource is contained in three mineralized pods adjacent to a dacitic done: the West, Central, and East pods. Exploration and production potential exists within the main resource area with the potential to expand mineralization at depth and to the southeast under post-mineralization volcanics and colluvium. Additional mineralization is contained in four outlying mineralized zones to the northwest: the San Antonio, North Breccia, CO8, and West Adit zones. The West adit is an under-explored zone. Only 1 properly-drilled hole tests the vein zone (2 holes total), and high-grade mineralization was encountered (11.5 g/t over 1.5m; see preceding section). The mineralization is open at depth and along strike. Additional mineralization in this area, which is near the main resource, could add to the overall resource tonnage

Geology: Tertiary (Miocene) volcanic sequence including ash-flow tuffs, tuffaceous sedimentary rocks and intrusive rhyolite flow domes and dikes. Paleozoic sedimentary rocks (argillites, greenstone, chert) underlie the volcanics; the contact is locally 75 to 200m beneath mineralized areas. Post-mineralization volcanic units locally conceal mineralization.

Ore(s): High-grade gold mineralization occurs within quartz veins, vein stockworks and breccia zones along northwest-trending structures. Mineralization also commonly follows the margins of intrusive flow domes and dikes. The strongest mineralization in the main resource area occurs where high-angle NW- and N-trending structures intersect a gently-dipping coarse-grained tuff, resulting in stratiform, gently-dipping mineralization within the tuff, marginal to the structures.

Other Databases

Link to USGS MRDS:	10310477

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References