New Mexico Cambrian alkaline rocks and REE veins

Region West, Southwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Alkaline/peralkaline igneous rocks include REE-carbonatites, REE-Th-U veins and disseminations in alkaline rocks in the Caballo, Telegraph, Pedernal Hills, Florida Mountains, Zuni Mountains, and Lobo Hill areas (modified from McLemore and Austin, 2017, fig.1).
Identified resources Historical production of barite, fluorite, and manganese.
Production Fluorite: small production in Zuni Mountains district (with byproduct barite). Approximately 8,900 tons of fluorite produced in Illinois Group from Caballo mountains. Harding deposit reported 865 tons of production. Manganese: a few hundred tons of ore (~ 17 to 38% Mn) produced from Caballos Mountain district (various MRDS records). Small production in Florida mountains (~ 21 to 30% Mn ore).
Status Past mining.
Estimated resources Unknown.
Geologic maps New Mexico Bureau of Geology and Mineral Resources (2003), scale 1:500,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Early Paleozoic alkaline rocks.
Deposits Fluorite: Zuni district: Mirabel (MRDS dep_id: 10013675), Juniper deposit (MRDS dep_id: 10013669), Bonita mine (MRDS dep_id: 10087749); Sierra Caballos district: Illinois Group (MRDS dep_id: 10110434). Manganese: Sierra Caballos area: Dakota Group (MRDS dep_id: 10011904), Hillside-Sierra Group (MRDS dep_id: 10011908), Lincoln Claim (MRDS dep_id: 10011912), Wild Horse Claim (MRDS dep_id: 10011922); Florida Mountains: Wet King Manganese mine (MRDS dep_id: 10013940), Birchfield Manganese mine (MRDS dep_id: 10013932).
Evidence from mineral occurrences MRDS; (McLemore, 2014).
Geochemical evidence Select samples of episyenites from the Red Hills area in the Caballo Mountains contain as much as 20,000 ppm Th, 1,600 ppm U, 500 ppm Nb, 5,000 ppm Y, 600 ppm Be, 7,500 ppm Ga and 200 ppm La (McLemore, 2014). Reanalyzed NURE stream sediment samples from the Florida Mountains contain 20-167 ppm Nb. TREE in the Florida Mountains is up to 734 ppm (Ervin, 1998). Grab sample from Zuni Mountain district contain 64 to 84% CaF2 and 0.6 to 0.8% BaSO4. Grab samples from Caballos area yield ~ 55% CaF2 and 0.2 to 1.1% BaSO4. Barite vein chip sample from Caballos yield 1% CaF2 and 88% BaSO4.
Geophysical evidence Inadequate aeromagnetic coverage.
Evidence from other sources None.
Comments Alkaline episyenites, nonfoliated, nonmetamorphosed igneous rock, cross-cut Proterozoic foliations and are enriched in REE, U, Th, Nb and other elements. The REE episyenite deposits are spotty, discontinuous tabular bodies, narrow lenses, and occur in breccia zones along faults, fractures and shear zones. Cambrian-Ordovician syenites and metasomatic bodies found in the Caballo, Zuni Mountains represent part of a Cambrian-Ordovician alkaline magmatic event in southern Colorado and New Mexico characterized by carbonatites, syenites, lamprophyres, episyenites and other alkaline rocks dated between 664 and 457 Ma (McMillan and McLemore, 2004). Mapping completed in Caballo, Burro; there is a need to focus on Lobo Hill and Lemitar Mountains that have potential for heavy REE. Also need to examine Nb potential in the Florida Mountains based upon reanalyzed NURE stream sediment samples.
Cover thickness and description Fluorite-manganese-barite deposits associated with veins and replacements in sedimentary rock, and therefore could be variably covered.
Authors Lukas Zurcher, Timothy S. Hayes, Virginia T. McLemore, Joshua M. Rosera.
New data needs Geochemistry and alteration mapping in the Florida Mountains.
Geologic mapping and modeling needs Alteration mapping.
Geophysical survey and modeling needs High resolution geophysical coverage needed (geophysical survey request completed).
Digital elevation data needs Lidar complete.