| Abstract/Notes | The oldest mines in the United States are in north-central New Mexico. Turquoise was mined before 900 A.D., lead and silver before 1600, and gold after 1828. Mining for base metals and coal began in 1880 but is now negligible. Since 1945, industrial nonmetals have been produced near Albuquerque.The Cerrillos (turquoise, lead, zinc, silver, copper), Old Placer (gold, tungsten), and New Placer (gold, copper, lead, zinc, silver, tungsten) districts are in a belt of early Tertiary monzonite stocks and laccoliths. Production from placers, breccia pipes, pyrometasomatic deposits, limestone replacement pipes, and veins has totaled about $11 million. "Red beds" copper deposits (Nacimiento district) and epithermal gold-silver veins (Cochiti district) have each yielded more than $1 million.Quaternary sediments of the Rio Grande provide sand and gravel. Brick and tile are made from Pennsylvanian and Cretaceous shales and building blocks of pumice and scoria from Quaternary volcanoes. A cement plant and two gypsum products plants, opened in 1959 and 1960, use limestone, dolomite, and shale from the Madera Formation (Pennsylvanian), gypsum from the Todilto Formation (Jurassic), and natural gas from the San Juan Basin. Annual production of nonmetals ranges from $9 to $13 million. Deposits of silica sand, bentonite, fluorspar, barite, marble, sulfur, perlite, and ocher are known but not currently (1966) worked.Near Cerrillos, 7 million tons of coking bituminous coal and anthracite have been mined; thermal metamorphism accounts for the rank. Elsewhere, bituminous coal occurs in folded and faulted coal beds of intermontane basins and subbituminous coal in flat-lying beds of the Colorado Plateau. The coals are Upper Cretaceous (Mesaverde and Fruitland formations). Reserves are estimated at 5 billion tons, including 53 million tons near Cerrillos. Although oil and gas production of the three-county area is not large, proximity to the San Juan gas field is a favorable economic factor. |
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