Mineralization in the Sierra Madre Mountains of West Central Mexico consists mainly of subvertical silver-gold veins cutting a flat lying felsic-mafic volcanic sequence. The Dolores deposit of Minefinders and the Ocampo deposit of Gammon Lake share many characteristics with the Santa Cruz Property, but the host rocks at Santa Cruz are limestones and conglomerates, not the andesitic and felsic volcanic rocks prevalent at the other deposits. At Delores, the veins are near feeder dikes and plugs, which are part of a major volcanic centre. Similar volcanic centres have not been identified near the Santa Cruz mineralization, but may be found by more detailed investigations as volcanic rocks dominate the regional geology. Near the Yesos adit the host rocks are moderately dipping white bedded limestones. Elsewhere the host rocks have been described as grey to dark grey limestones. According to the Mexican Government Geological Survey (CRM) the lower westerly adits lie within a conglomerate. The contact with the overlying limestone seems to dip moderately southeasterly at about 20 degrees.