New Mexico Geological Society Annual Spring Meeting — Abstracts

The Hermosa mining district is located 30 miles west ofTruth or Consequences, New Mexico in the eastern Black Range. The district produced 1.25 million oz of silver, 47,600 lbs oflead, 8000 lbs ofzinc, 1,850 lbs ofcopper and 3 oz ofgold from 1879 to 1891 from carbonate hosted lead-zinc deposit.

The ore bodies are localized by faults in Paleozoic sediments of Permian to Ordovician age. Small Tertiary igneous bodies intrude the sediments locally and are believed to have provided the heat and some of the fluids necessary for the metals found in the ore bodies.
Interpretation of geochemical data of the igneous bodies suggests two intrusive events that may be related to multiple phases of ore genesis.

Primary ore minerals include argentite, galena, sphalerite, chalcopyrite, bornite, pyrite, and gold. Secondary minerals include azurite, cerusite, chalcocite, chrysocolla, cuprite, descloizite, malachite, mimetite, smithsonite, vanadinite, and wulfenite. Identification of samples from faulted and altered zones by X-ray diffraction indicate the presence of calcite and talc, which surround the mineralized bodies throughout the district. Barite and quartz are also found in the altered zones.

Compilation and interpretation of published and unpublished geochemical data ofthe replacement ore bodies in the district indicate a lack of district zonation. Low correlation of silver with zinc and lead throughout the district suggests that silver minerals are the primary source of silver in the district as opposed to silver disseminated in other sulfides.