Mineral deposits in Rio Arriba County, New Mexico

—More than $40 million worth of mineral production has come from 14 types of deposits in 19 mining districts in Rio Arriba County. Three of these districts (Nacimiento, Jemez pumice, No Agua) are considered significant deposits for copper, silver, and pumice, although known large deposits are in adjacent counties (Taos, Sandoval). However, the presence of these significant deposits and the potential for discovery of additional metals resources in the Bromide No. 2 and Hopewell districts in Rio Arriba County should encourage exploration in the county. Despite the presence of remaining resources of feldspar, mica, niobium, rare-earth elements, and beryllium, it is unlikely that the pegmatites in the Petaca and Ojo Caliente districts will ever produce again because of small size and grade. Only the Menefee Formation coal at shallow depths has limited economic significance in the Moreno coal field, where preliminary estimates indicate demonstrated resources at a depth of 61 m are 8 million short tons. Currently only aggregate pits (sand and gravel, scoria, pumice) are active and production of aggregate (sand and gravel, pumice, and scoria) is likely to continue in the future. FIGURE 1. Mining districts in Rio Arriba and adjacent Counties, New Mexico. 446 MCLEMORE AND HOFFMAN provisions to obtain private ownership of federal land containing valuable mineral resources. The act was subsequently amended in 1870 and 1872 and in the years since. The mining act further encouraged mining and prospecting in Rio Arriba County and elsewhere in New Mexico and the mining boom of 1870-1890 began. Many districts in Rio Arriba County began to open up and production began as the Apache Indian threat was subdued (Table 1). The telegraph and then the railroad improved conditions in the area as mining continued to flourish. New metallurgical techniques were developed. Times were exciting for the miner in the late 1800s as metal prices soared. The 1870s and 1880s saw growth in mining in many districts in Rio Arriba County. Silver became important in 1870-1880s in many districts. In 1890 the Sherman Silver Act was passed which increased the price and demand for silver. However, it was short lived. The Sherman Silver Act was repealed in 1893 and most TABLE 1. Mining districts in Rio Arriba County, New Mexico. Names of mining districts are after File and Nothrop (1966) wherever practical, but many districts have been combined and added. Commodity symbols are defined in Appendix 1. District identification number is from the New Mexico Mines Database (McLemore et al., 2005). Estimated value of production is in original cumulative dollars and includes all commodities in the district, except aggregate (sand and gravel) and crushed and dimension stone. Production data complied from Lindgren et al. (1910), Anderson (1957), U. S. Geological Survey and Bureau of Mines Mineral Yearbooks (1900-1993), and Energy, Minerals and Natural Resources Department (1986-2003). Types of deposits are after North and McLemore (1986) and McLemore (2001). * district contains a significant deposit. Locations of districts are in Figure 1. Under commodities, commodities in parenthesis are occurrence only, other commodities listed were produced. District id District Year of Discovery Years of Production Estimated Cumulative Production Commodities (occurrence only) Types of deposits DIS137 Abiquiu (Arroyo del Cobre, Chama Basin) 1859 (probable early Spanish mining) 1954 $1000 U, V (Cu, Ag, Au) sedimentary-copper, sandstone uranium, limestone uranium, placer gold DIS138 Box Canyon 195