New Mexico Mineral Symposium — Abstracts

Socorro Peak (elevation: 7,280 ft) is located approximately 4 miles west of Socorro, Socorro County, New Mexico. The Socorro Peak mining district is centered southeast of the peak, low on the east slope. Smaller mines and prospects extend to the north and south, and toward the crest. Silver was discovered in the district in 1867 by prospectors from nearby Magdalena. Silver production peaked by 1880 and terminated in the mid 1890's, producing $760,000-1,000,000 in silver yalues; however, profits were low.

Socorro Peak is made up of Tertiary volcanic rocks (trachytes, rhyolites, andesites, and tuffs) and interlain sediments. These rocks rest on a thick series of Pennsylvanian rocks (Magdalena group) which overly Precambrian granite. The whole sequence is faulted and dips to the west.

The ore zone on the east face of the mountain is the most complexly faulted. There are two general systems of faults. The most prominent group strike roughly parallel to the elongation of the Socorro Mountains (N20W-N15E). The second group dip steeply and strike N60°E-N70DE. These faults provided channels for subsequent mineralization, thus the veins are all fault controlled, occurring mostly in trachytes, spherulitic rhyolite, and limestone.

The Merrit and Torrance mines were the only commercially productive veins of the Socorro Peak district. These two veins could be faulted segments of the same vein. Inclined shafts were sunk along the veins to recover the ore which consisted of sparsely disseminated silver halides and traces of malachite. The best ore was said to occur associated with fluorite but at best averaged 15-20 oz Ag/ton. Mining terminated in the Torrance and Merrit Mines where the veins were faulted out. The Silver Bar mine is located on the faulted segment of the Merrit vein, which was displaced 50 ft to the west by a fault striking near east-west dipping 75°N.

The primary vein minerals are barite and quartz with lesser amounts of calcite, fluorite and Mn oxides. The most interesting of the minerals are the secondary lead and copper and zinc minerals. Mimetite, wultenite, hemimorphite, willemite, anglesite, and mottramite constitute the suite of known secondary minerals. For the most part these minerals are distributed evenly throughout the mines in the district. The notable exception is mottramite. Mottramite appears to occur along a faulted zone which trends N69°W. The main occurrence does not come from a mine but occurs at a surface exposure of a fault. The lead minerals are oxidation products of the galena which occurs only sparingly in the barite. Wulfenite was found by the authors only at the Silver Bar Mine and an unnamed mine near,the peak. Though thought to occur in the district, no vanadinite was found.