Geology, alteration, and genesis of the Luis Lopez manganese district, New Mexico
— Ted L. Eggleston, David I. Norman, Charles E. Chapin, and Samuel Savin

The Luis Lopez manganese district consists of a group of epithermal manganese deposits located in the northern Chupadera Mountains, southwest of Socorro, New Mexico (fig. 1). The district was one of the largest producers of manganese in New Mexico; as of 1957, total production in the district was 97,000 short tons of concentrate that averaged about 41 percent Mn and 18,000 short tons of crude ore that averaged 28 percent Mn (Farnham, 1961; Willard, 1973). Production continued until the early 1970's, but much of this later production has not been reported. The most productive mines in the district were the MCA, Tower, Nancy, and Black Canyon. The manganese was produced from both open pit and underground operations in fissure veins and breccia zones along steeply dipping faults. This paper reports the results of geochemical and stable isotope investigations of alteration associated with the manganese mineralization and stable isotope investigations of the vein material.