Mineral Resources in Union County, New Mexico
— Virginia T. McLemore

Mining played a minor role in Union County’s history in the early- to mid-1900s, when four mining districts were developed: Black Mesa, Peacock Canyon, Northeastern Union County, and Folsom. More than 120 clastic plugs, many containing copper, silver, and uranium minerals, have been identified in the Black Mesa district of the Dry Cimarron Valley of New Mexico that extends into southeastern Colorado (Carrizo district) and western Oklahoma. Copper, silver, and minor gold were produced from deposits in the Black Mesa (New Mexico) and Carrizo (Colorado) districts. Sedimentary-copper deposits were first located in the Peacock Canyon district in 1900, but no production occurred. Known sandstone-hosted uranium deposits in the Morrison Formation in the Northeastern Union County uranium prospect area are small, low grade, and uneconomic. Three types of mineral deposits are found in the Folsom district (quartz with minor gold veinlets in basalt, placer gold, and scoria), but only the scoria deposits have been produced for railroad ballast, natural lightweight concrete aggregate, road surfacing aggregate, and cinder (or building) block manufacture. Around 2010-2012, Dumas Ventures LLC leased thousands of acres in the Clayton area for exploration for placer gold and received a mining permit from the New Mexico Mining and Minerals Division. No gold production has occurred and there is no resource potential for economic placer gold deposits anywhere in Union County with a high degree of certainty. In addition, aggregate (sand and gravel), clay, coal, and building stone have been developed in the county.