Geology and mineral resources in the Zuni Mountains mining district, Cibola County, New Mexico: Revisitied
Virginia T. McLemore
The Zuni Mountains district is in the central and southern Zuni Mountains in north-central New Mexico. The earliest mining in the Zuni Mountains was by Native Americans, who recovered obsidian (eroded from the Mt. Taylor region), basalt, turquoise, malachite, azurite, and possibly fluorite for ornaments and stone tools. The major types of deposits in the Zuni Mountains include 1) veins and replacements in Proterozoic rocks, 2) stratabound, sedimentary-copper deposits, and 3) fluorite veins, although 4) REE (rare earth elements)-Th-U metasomatic bodies, 5) high-calcium limestone, 6) volcanic cinders (scoria), and 7) iron deposits also are found in the Zuni Mountains district. Total fluorite production exceeded 224,000 short tons of crude ore. Total reported metals production from the district amounts to more than 30,000 pounds copper, 260 oz silver, and 2 oz gold from 1923 to 1965; additional copper, gold, and silver production probably occurred during the late 1800s. There is some economic potential for gold, silver, and possibly copper in the veins and replacement deposits in Proterozoic Zuni and Mt. Sedgwick granites and metarhyolite. The Proterozoic dark syenite and amphibolite bodies and gold-silver veins in the Zuni Mountains should be geochemically evaluated for their platinum group metals (PGE) potential. It is unlikely that the stratabound, sedimentary-copper deposits or fluorite veins have any remaining significant economic potential, because the highest grades have been mined and remaining deposits appear to be discontinuous and low grade. The REE-Th-U metasomatic bodies and iron deposits also have low economic potential because of low grade and small size. The Zuni Mountains continue to have high economic potential for high-calcium limestone and volcanic cinders (scoria). The veins and replacement deposits appear to be Proterozoic in age and are associated with the Zuni and Mt. Sedgwick granites and metarhyolite, while the late Proterozoic episyenites appear to be associated with the Mt. Sedgwick granite. The fluorite veins are much younger and perhaps associated with other Rio Grande rift barite-fluorite deposits in New Mexico.
- McLemore, Virginia T., 2013, Geology and mineral resources in the Zuni Mountains mining district, Cibola County, New Mexico: Revisitied, in: Geology of Route 66 region: Flagstaff to Grants, Zeigler, Kate; Timmons, J. Michael; Timmons, Stacy; Semken, Steve, New Mexico Geological Society, Guidebook, 64th Field Conference, pp. 131-142.