New Mexico Mineral Symposium — Abstracts

During the last five years a number of discoveries of secondary lead-copper-zinc minerals have been made in the San Juan Mountains of southwestern Colorado. The minerals generally occur in the upper part of mineralized veins and replacement orebodies that have been oxidized near the surface. The exotic and colorful minerals do not occur in large quantities as in New Mexico and Arizona but do occur as well-crystallized microminerals in the vuggy gossan zone.

In San Juan County, probably the best-known locality for secondary minerals is the Titusville mine at the head of Kendall Gulch at an elevation of 12,920 ft. To date the following secondary minerals have been identified: anglesite, azurite, brochantite, cerussite, halcoalumite, linarite, malachite, ozarizawaite, posnjakite, serpierite, and smithsonite.

Also in San Juan County, the Bandora mine has produced well-crystallized microcrystals of cerussite, linarite, pyromorphite, and wulfenite.

Moving north to Ouray County, the best locality for secondary minerals are the Senorita, Black Girl, and Slide mines on Carbonate Hill in the Paquin mining district. The primary ore consists of galena and tetrahedrite as replacement orebodies in sedimentary rocks adjacent to steeply dipping mineralized veins. Vugs in the quartz-barite contain beautiful microcrystals of the following minerals: aragonite, anglesite, aurichalcite, azurite, bindheimite, bronchantite, cerussite, cuprite, langite, linarite, malachite, mimetite, pyromorphite, rosasite, silver, smithsonite, and wulfenite.

The Mineral Farm mine, which consists of a number of shafts, declines, and prospect trenches, has produced fine specimens of aurichalcite, azurite, and malachite.

Other small prospects in both counties have produced anglesite, azurite, cerussite, linarite, and malachite.