The project area is predominantly underlain by Upper Cretaceous intrusive rocks of granodiorite to quartz monzonite composition locally overlain by Lower Tertiary rhyolites and andesites. The dominant structural features in the region strike northwest-southeast. The intrusives host epigenetic native silver veins such as those of Batopilas (near Guadalupe) approximately 60 km to the north of La Fortuna, as well as fracture-controlled and disseminated precious metal and copper deposits. The Tertiary volcanics host several epithermal precious and base metal deposits such as the mines at Topia approximately 40 km to the east of La Fortuna but are unmineralized in the project area.
The project area hosts numerous historic adits and gold-silver showings including the historic La Fortuna Mine (and extensions) and the Ramada, PN, and Cerro Pelon to name a few.
The La Fortuna deposit consists of hydrothermal breccias, quartz-tourmaline veining and intense silicification. The mineralization is spatially associated with a series of parallel fault structures approximately 1.5-2.0 km apart and related tourmalinized quartz monzonite breccia bodies that flank a tabular NNW striking quartz monzonite intrusive. Mineralization remains open at depth and along strike. Similar style mineralization occurs at surface approximately 400-500 m south of the current resource and can be traced along strike for at least 200 m.
Mineralization consists of up to 10% disseminated and stockwork pyrite and chalcopyrite with minor tetrahedrite, sphalerite and galena. The mineralization appears to be associated with tourmaline, quartz, chlorite and epidote and is mostly restricted to the highly tourmalinized areas.