New Mexico Mineral Symposium — Abstracts

Well crystallized brochantite was discovered in 1981 in northern Garvin County near the community of Paoli. The deposit is particularly interesting mineralogically because of its assemblage of copper-bearing minerals in a "red bed" occurrence.

The host rocks for the copper mineralization are Permian sandstones belonging to the Garber formation. These sandstones occur throughout much of northern Texas and some southwestern states, as well as Oklahoma, and contain copper minerals in isolated locations. Many of these other deposits may contain similar mineral groupings if favorable formation conditions exist.

The brochantite was formed within 3 ft of the present land. surface on the underside of a sandstone ledge containing barite cement. Other specimens of brochantite developed on sulfide nodules embedded within a clay layer beneath. Meteoric water undoubtedly played a major role in the creation of the deposit, particularly the development of the brochantite.

The brochantite crystals are stubby, small (less than 1 mm), and cover from 10 to 90% of the rock surfaces. The crystals are sometimes intergrown to form a botryoidal surface several mm thick.

Other minerals found in the area include malachite, azurite, chalcanthite, chrysocolla, barite (cement, radial balls, "rose rocks," and claystone geode fillings), hematite, silver minerals, calcite, aragonite, goethite, cuprite, pyrite, chalcocite, and several unknown minerals (probably copper sulfates).

The area was mined around the turn of the century, but the very small, open-pit copper mines were not profitable. Silver was mined profitably in the region about 70 years ago. Limited prospecting for copper minerals was begun in the region around 1980.