The relief of the mountain is held by Granitic Massif São Francisco or simply Granite São Francisco, which is an elongated body according to a northeast-southwest intrusive metasedimentary rocks of the São Roque Group. It is a biotite granite dominant pink color, composition syenogranitic with fluorite as locally accessory amphibole and sodic. It subalkaline nature, type A, with locally rapakivi texture. Form extensive fields and rocky boulders. The age of this granite is Neoproterozoic, estimated at 560 million years. It is one of the granites with high natural radioactivity of the state of Sao Paulo, either by their frequent exposure of rocky, with fractures, either by the same mineralogical composition. The highest values of natural radioactivity are recorded in the canyon of the Sorocaba River, downstream from the Dam Itupararanga. At the time of World War II was to search tungsten in the São Francisco Ridge. The work was done by geologist Theodoro Knecht, who described the mineral occurrences of tin and wolframite in the western portion of the mountain, and endograisens associated with quartz veins. Adjacent to the northern flank of the São Francisco ridge are the mining of limestone for cement Votorantim Group, the factories of St. Helena and Santa Rita, and other mines near the Pirapora river in the west part of the ridge. Along the eastern edge of the mountain is the municipality of Aluminium, next to the aluminium plant of Companhia Brasileira de Aluminio (CBA).