Chalcopyrite with Quartz & Pyrite

Chalcopyrite with Quartz and Pyrite from Casapalca, Huarochiri Province, Lima, Peru, measuring 92 × 58 × 42 mm and weighing 225 grams. A good solid sulfide specimen from one of the classic mining districts of the Peruvian Andes.

Chalcopyrite is copper iron sulfide, CuFeS2, and its brassy, often iridescently tarnished crystal faces make it one of the most immediately recognisable sulfides, while Pyrite, iron disulfide, is its paler, harder, more golden cousin, commonly found growing alongside it in the same hydrothermal veins. Casapalca's orebodies formed in the Central Peruvian polymetallic belt, where silver-lead-zinc-copper mineralisation was deposited in veins and replacement bodies associated with Andean volcanic and intrusive activity, with Quartz as the dominant gangue mineral carrying the metallic sulfides.

Casapalca has been one of Peru's significant mines for well over a century, and specimens combining its principal sulfides with well-formed Quartz, as this one does, are a good way to show the mineralogy of a working Andean polymetallic mine rather than just its most famous individual species. This piece carries a double provenance, the David Vince Collection and Willyama Minerals.