Geology Sao Chico

Outcrop at Sao Chico is poor due to widespread laterite development and alluvium. The average depth to fresh rock is approximately 10 to 20 meters. The cover comprises a red, lateritic top soil between one and three meters deep, with a lower boundary marked by a stone line or pesolith of quartz fragments and ferruginous pebbles. Saprolitic bedrock underlies the laterite and ranges in depth from 10 to 20 meters below surface, with a gradational transition into fresh host rock. Quartz float at surface overlies quartz vein zones, and float trains were used as a prospecting tool by artisanal miners in the region.

Sao Chico is underlain by Early to Middle Proterozoic granite and granodiorite of the Pararauri Suite, which is also the host to mineralization at the Palito and Tocantinzinho deposits. Host rocks at Sao Chico are composed of granodiorite and granite, typically medium-grained, leucocratic, feldspar phyric and belonging to a larger, poorly exposed intrusive complex.

Mineralization is hosted in west-northwest trending, steeply south dipping fault zones with a shear component. These mineralised faults have been offset by north to north-northeast trending normal faults with a dextral lateral displacement.