Geochemistry of the Tajo Granite, Socorro County, New Mexico
— Haley M. Dietz and Virginia T. McLemore

The Proterozoic Tajo granite consists of six outcrops along two northwest-striking faults east of Socorro, New Mexico. The area was originally examined for uranium, but fluorite and rare earth elements (REE) are reported as well (Fieldman, 1977). REE consist of the 15 lanthanide elements, including scandium and yttrium, and are fundamental to modern society. Although common in the crust, REEs are not often found in economically viable concentrations. Some Proterozoic granites in New Mexico, including the Tajo granite, were exploration targets for uranium and REE, but their economic resource potential is unknown. We conducted a petrographic and geochemical study of the Tajo granite to determine its mineral-resource potential. The Tajo granite is a medium- to coarse-grained, peraluminous, A-type granite. Geochemical comparisons of the Tajo granite to two other Proterozoic granites found in central New Mexico that are associated with REE deposits, the Gallinas and Sevilleta granites, show that individual granite bodies have variable REE compositions but the three are approximately similar in total REE. The REE and U are below economic concentrations in the Tajo granite and therefore, the miner-al-resource potential of the Tajo granite is low.