The Orogrande Gold Project is hosted within or at the edge of the Orogrande Shear Zone, a 40 km long north-south regional shear zone roughly at the contact between the Cretaceous Idaho Batholith and metamorphosed Proterozoic Belt-Purcell sedimentary rocks. The shear zone, or at least discrete faults associated with the shear zone, are reported to range from 100 to 200 m in width. Metasedimentary rocks along and in contact with granodiorite cover a large area within the shear zone. Numerous leucocratic pegmatite and aplite dykes along with small late Cretaceous to Tertiary felsic intrusions are present in the area. These features appear to be closely associated with areas of gold mineralization. The Orogrande Gold Project falls just on the edge of a southern portion of the shear zone. Gold mineralization in the district can be classified into two types with native (high grade) gold associated with quartz vein lodes and lenses within granodiorite, dacite or at contacts between granodiorite and metasedimentary schist and/or gneiss. The second type of gold mineralization is associated with zones of disseminated pyrite in silicified shear zones and breccias sometimes with a network or stock work of thin veins and veinlets.