Geology & Mineralization
The Silver Crown mining district, within which the Copper King project is located, is underlain by Proterozoic rocks that make up the southern end of the Precambrian core of the Laramie Range. Metavolcanic and metasedimentary rocks metamorphosed to amphibolite-grade are intruded by the approximately 1.4 billion-year-old Sherman Granite and related felsic rocks. Within the project area, foliated granodiorite is intruded by aplitic quartz monzonite dikes, thin mafic dikes, and younger pegmatite dikes. Shear zones with cataclastic foliation striking N60°E to N60°W are found in the southern part of the Silver Crown district, including at Copper King. Copper and gold mineralization at Copper King occurs primarily in unfoliated to mylonitic granodiorite. The granodiorite typically shows potassium enrichment, particularly near contacts with quartz monzonite. At Copper King, mineralization is associated with a N60°W-trending shear zone.
Copper King mineralization has been interpreted as a shear-zone controlled, disseminated and stockwork gold-copper deposit in Proterozoic intrusive rocks. Most of the mineralization is in granodiorite, with lesser amounts in quartz monzonite and thin mafic dikes. Hydrothermal alteration is overprinted on retrograde greenschist alteration and includes a central zone of silicification, followed outward by a narrow potassic zone, surrounded by propylitic alteration. Higher-grade mineralization occurs within a central core of thin quartz veining and stockwork mineralization that is surrounded by a zone of lower-grade disseminated mineralization. Disseminated sulfides and native copper with stockwork malachite and chrysocolla are present at the surface, and chalcopyrite, pyrite, minor bornite, primary chalcocite, pyrrhotite, and native copper are present at depth. Gold occurs as free gold. About 80% of the resource is sulfide material, while the remaining 20% is split equally between oxide and mixed material.