New Mexico Mineral Symposium — Abstracts

Spangolite, the rare copper sulfate (Cu₆Al(SO₄)(OH)₁₂Cl•3H₂O), was recently found to occur at the Buckhorn mine in the Red Cloud district of the Gallinas Mountains Previously known New Mexico localities for this species are restricted to the Hansonburg mining district and a single occurrence at the Kelly mine in Socorro County. The Buckhorn mine lies in the northern portion of the Gallinas Mountains about eight mi southwest of Corona in Lincoln County, New Mexico. Perhac (1970) reported several supergene copper and lead minerals from this mine including pyromorphite, anglesite, chrysocolla, malachite, and azurite. Recent investigations of supergene minerals from the Buckhom mine have established 12, possibly 13, additional species. These include the sulfates brochantite, cyanotrichite, celestite, linarite, and spangolite. Although arsenates and vanadates have not previously been reported from this mine, duftite, mimetite, olivenite, mottramite, and vanadinite were found to occur. Arsentsumebite has been tentatively identified (by microprobe/SEM) but additional analyses (x-ray diffraction) are required for confirmation. The lead molybdate, wulfenite, was also found in very small amounts. Previous reports of pyromorphite could not be substantiated.

Spangolite crystals are found in association with free-standing, bright-green sprays of brochantite and mostly flat-lying sprays of light-blue cyanotrichite. Spangolite crystals are generally a lustrous blue green and are transparent to translucent. Although spangolite is hemihedral, being in the ditrigonal pyramidal crystal class, it usually assumes a morphology that looks holohedral, consisting of striated hexagonal prisms terminated by hexagonal pyramids. A few crystals exhibit small pedial terminations while others have large pedial faces, give which give them a blocky appearance similar to spangolites from the Hansonburg district. Buckhom spangolites range in size from 0.5 to 3.0 mm.

Extensively fault-brecciated, Permian Yeso sandstone/arkose forms the host rock for these minerals (Perhac, 1970). Tertiary intrusives are responsible for the mostly fissure-filling, mineralizing solutions that deposited the primary or hypogene ore minerals of fluorite, galena, and bornite. Bastnaesite, for which the Red Cloud district is famous, was not noted at the Buckhom mine either by Perhac or by the authors.
 

References:

1. Perhac, R. M., 1970, Geology and mineral deposits of the Gallinas Mountains, Lincoln and Torrance Counties, New Mexico: New Mexico Bureau of Mines and Mineral Resources, Bulletin 95, 51 pp.