The Peñoles property lies in the Altiplano Sub province of the Sierra Madre Occidental (SMO). The SMO is a regionally extensive Eocene to Miocene volcanic field that extends from the US-Mexican border into Central Mexico. The Altiplano sub province is on the eastern flank of the SMO and comprises Jurassic to late Tertiary sedimentary and volcanic rocks (Sedlock et al., 1993). This district hosts extensive hydrothermal-related silver, gold and base-metal deposits and is generally referred to as the Faja de Plata, or Mexican Silver Belt.
The El Capitan deposit, the Jesus Maria deposit, and the San Rafael-El Tubo prospects of the Peñoles Project are located on the concessions owned by Riverside and they appear to be related to intersections between the northwest-striking and northeast-striking regional structures. These occurrences are also localized along the southern margins of a northeast-oriented magnetic anomaly identified from government airborne surveys.