New Mexico Mineral Symposium — Abstracts

The Cerrillos mining district includes perhaps the oldest underground mine in the United States. Mineralization in the southernmost mineralization center of the district is coincident with a mid-Tertiary monzonite with concentric alteration typical of copper porphyries of the southwestern U.S. The three following types of mineralization occur in this mineralization center:
a disseminated copper sulfide deposit lying near the monzonite, turquoise deposits present in argillically altered rock concentric about the monzonite, and late base-metal veins which cut the monzonite.

The Mina del Tiro and parallel veins contain a simple base-metal sulfide suite which has produced a great variety of minerals upon oxidation. Sulfides include sphalerite, galena, pyrite, chalcopyrite, and tetrahedrite. Oxidation products include hemimorphite, aurichalcite, cerussite, plattnerite, wulfenite, and descloizite.

Particularly unusual are the black color of the wulfenite and common pseudomorphs of plattnerite after cerussite.