Geology of the Fra Cristobal Mountains, New Mexico
— W. John Nelson, Spencer G. Lucas, Karl Krainer, Virginia T. McLemore, and Scott Elrick

The Fra Cristobal Mountains are a small north-trending range situated on the east side of the Rio Grande northeast of Truth or Consequences. The range is an east-tilted horst of Proterozoic granitic rocks overlain by Paleozoic, Mesozoic, and Cenozoic sedimentary formations. Paleozoic rocks comprise the Cambro-Ordovician Bliss Formation, Ordovician El Paso Formation and (locally) Montoya Formation, Pennsylvanian Red House, Gray Mesa, Bar B, and Bursum formations, and Permian Abo Formation, Yeso Group, thin Glorieta Sandstone, and San Andres Formation. Representing the Mesozoic are the Cretaceous Dakota Sandstone, Mancos Shale, and Crevasse Canyon and McRae formations. Mantling the flanks of the range is the Cenozoic Palomas Formation of the Santa Fe Group along with younger, unnamed Quaternary deposits. Flows, cinder cones, and dikes of Upper Pliocene olivine basalt occur in several areas in and near the range. The Fra Cristobals underwent Laramide compressional deformation followed by Cenozoic extensional faulting and uplift related to the Rio Grande rift. Small deposits, chiefly fault-controlled veins, of gold, silver, copper, lead, fluorite, and manganese have been prospected, but no significant mining has taken place in the range.