Calcite–pyrite specimens from the Huaron Mining District in Cerro de Pasco, Peru, form in high-altitude, polymetallic hydrothermal veins (around 4,000 m elevation) at mines such as Animón and San Cristóbal. Golden, striated pyrite cubes often serve as a base for overgrowths of scalenohedral or rhombohedral calcite crystals and are frequently associated with clear quartz and sphalerite matrix. Collectors prize these pieces (this is a good example) for the striking contrast between the metallic luster of pyrite and the translucent, sharply faceted calcite, and some specimens exhibit bright orange fluorescence under short-wave UV light.