Geology and Mineralization

Certej is an intermediate sulfidation epithermal gold deposit associated with a Miocene magmatic complex in the South Apuseni Mountains, Romania. Gold mineralization is hosted within Cretaceous sedimentary rocks (black shales and intercalated siltstones to sandstones) and Neogene conglomerates, grits and volcanic and intrusive units. Three main andesitic intrusive phases are recognised in the deposit; Dealu Grozii, Baiaga and Hondol, with the Baiaga Andesite located in the center of the system and mineralization developed along the intrusive contacts, within the Cretaceous and Neogene sedimentary rocks and in the Hondol and Dealu Grozii Andesites. Mineralization has a broad E-W orientation with higher grade breccia zones oriented along NW-SE and NE-SW structures. Ore styles include disseminated mineralization in sedimentary units and at the contacts of intrusive rocks, hydrothermal breccias, stockworks and distal veins. The gold occurs with pyrite in arsenic-rich rims together with variable amounts of sphalerite and galena. Native gold is present but restricted to the distal veins. Zonation is observed both in the style of mineralization and alteration patterns with widespread clay-sericite-pyrite-calcite surrounding a core of silica-adularia.