New Mexico Mineral Symposium — Abstracts

Barite-fluorite-galena veins occur along a fault zone in limestones, sandstones, and siltstones of the Permian Yeso Forma-tion and sandstones of the Permian Glorieta Sandstone Member of the San Andres Formation at El Cuervo (Crow) Butte in southern Santa Fe County, New Mexico. The fault dips steeply to the west and trends northeast. Mineralization has been traced for almost three miles along the fault. Barite veins and pods up to 1 ft wide occur throughout the 3-5-ft-wide fault zone. Mineralized veins are common along fractures and bedding planes of Permian rocks adjacent to the fault. A second, unmineralized fault occurs to the west of the mineralized fault and separates the Glorieta Sandstone Member from shales of the Triassic Chinle Formation.

Barite is the dominant mineral, however, fluorite and argentiferous galena are common in pockets and zones within the veins. Other accessory minerals include calcite, quartz, sericite, potassium feldspar(?), and a trace of chrysocolla. The barite is typically white or pink and opaque, whereas fluorite is white, green, or purple and clear to translucent. Specimens of green fluorite fluoresce bluish-purple.

Samples from the deposit contain up to 87.77% BaSO₄. Additional samples contain up to 2.31% Pb, 0.01% Zn, 0.22 oz/ton Ag, and a trace of gold (less than 0.02 oz/ton). Analyses of white barite crystals yield 80-328 ppm Pb, 6-12 ppm Cu, 2-4 ppm Zn, <10 ppm Cr, 25-244 ppm Mg, 5 ppm Mn, 34-99 ppm K, 29 ppm Na, 19-23 ppm Y, 1.45-1.59% Sr, and 0.51-1.12% Ca.

The deposits at El Cuervo Butte are similar in emplacement, geology, mineralogy, and chemistry to sedimentary hydrothermal deposits and are analogous in part to Mississippi Valley-type deposits. Deposits that are probably of sedimentary hydrothermal origin are widespread within or near the Rio Grande rift. Examples may be found at Hansonburg, Palomas Gap, and Salinas Peak.