Papers - Mining Geology - Geology of the Parral Area of the Parral District, Chihuahua, Mexico (With Discussion)

The Parral area, a part of the Parral mining district of Southern Chihuahua, is situated in and near the City of Parral, with the most important mine of the district, La Prieta, lying within the city limits. The famous Veta Colorado and Palmilla veins near Villa Escobedo or Minas Nuevas are a few kilometers to the northeast (see Fig. 1). The chief metals produced are silver, lead and zinc, with some copper and gold. This area was one of the earliest to produce metal in Mexico, according to records at Parral, which show that mining started in 1632. In near-by Santa Barbara, however, mining had begun 85 years earlier. It is said that when silver was discovered in the Veta Colorado, the Santa Barbara gold deposits, at that time nearly exhausted, were immediately abandoned for the more profitable silver mines at Minas Nuevas (New Mines) During the post-revolutionary period, 1923-1928, the author made many trips to the Parral district to do mine examination work for several units of the American Smelting and Refining Co. This paper is an abstract of some of the geologic data collected, together with the results of a microscopic study of the ores and rocks—the latter investigation made at the University of Minnesota—and is intended to supplement one recently published. Topography The Parral district lies in the eastern foothills belt of the Sierra Madre Oeste. The area is about evenly divided between fairly flat to rolling plains and mesas on the south and rounded hills to rough precipitous slopes on the west and north. The relief is approximately 550 m. (1800 ft.). The areas of intrusive monzonite and Jurassic (?) sedimentary rocks give rise to a topography of low rounded hills and relatively flat valleys; as contrasted with the volcanics, with their alternating beds of soft