Pecos Mine's Ancient Riches: Precambrian Geology & Ore Deposits

Four trondhjemitic bodies — three of intrusive and one of extrusive origin — 1. 7 to 1. 8 b. y. In age occur in the precambrian rocks of northern new mexico and southwestern colorado. From 1926 through 1939, amcnm developed and operated a lead and zinc mine, commonly known as the pecos mine or tererro mine, located approximately 16 miles north of the village. Anomalous amounts of silver and/or gold have been identified in 153 mining districts or prospect areas of new mexico. Production from most of these occurrences has been small;

Riesmeyer (1978) discusses the precambrian volcanic and sedimentary geology, and the ore deposits of the pecos mine area in more detail than the present summary. The pecos ores were probably deposited by hot metalliferous fumarolic solutions on the precambrian sea floor. The nature and stratigraphic suc­cession of various ore types are. The ore deposits formed a zone 60 ft wide in this. Detailed mapping around the pecos mine by riesmeyer (1978) convincingly documents the volcanogenic nature of that deposit. Riesmeyer and robertson (this guidebook) describe the.