New Mexico Mineral Symposium — Abstracts

The Bear Mountains mining district is located in the Cibola National Forest, T. 4 N., R. 4 W., about 15 miles north of Magdalena. The prospects are located near the head of Cedar Springs Canyon.

The mineralization of the district is found along a fault that cuts La Jara Peak Basaltic Andesite and Hells Mesa Tuff. All prospects and shows of mineralization are located in places where the fault cuts La Jara Peak Basaltic Andesite. The mineralized portions of the fault strike roughly north-south and dip steeply to the east. Hematite alteration is pervasive along the fault. Epithermal copper-antimony mineralization is exposed by two open cuts. The exposed vein varies up to 1 ft wide.

Observed primary minerals include only pyrite, quartz, and calcite. Oxidized minerals include abundant chrysocolla, hematite, tripuhyite (FeSb₂O₆), stibiconite (Sb⁺³Sb²⁺₅O(OH)), and unidentified antimonate. The unidentified mineral has an x-ray diffraction pattern identical to ordonezite (ZnSb₂O₆), but it contains no zinc and has copper as a major constituent. The mineral is suspected to be the copper analog of ordonezite. Conichalcite was found in small amounts. Assays showed only as high as 0.75 oz/ton (25.7 ppm) silver and no gold.

The presence of relatively large amounts of antimony suggests that this deposit contained. stibnite and perhaps tetra-hedrite as primary minerals. The resulting oxidized products make the mineralogy of this deposit unique in New Mexico.