5.15" Lustrous Sphalerite on Fluorescent Manganoan Calcite - Peru

The Casapalca Mine in Peru is situated about 4500 meters above sea level, where the boundaries of Lima begin to transition into the Andes Mountains. The rough location falls within the Huarochiri Province of the Lima Department in Peru. This mine is notable for its rich deposits of lead, zinc, silver, and copper ores. However, it also produces some especially fine mineral specimens, similar to those coming out of Peru's famous Huanzala Mine in Ancash. The most common minerals from this locality are quartz, sphalerite, galena, pyrite, chalcopyrite, dolomite, barite, rhodochrosite, and manganoan calcite (aka manganocalcite). Often, many of these minerals occur in multi-mineral jumbled associations that make stunning display pieces.

Casapalca Mine also has another interesting feature: bisecting the primary vein is a parallel deposit that, for all intents and purposes, should not be there. This other vein does not match the stratigraphy of the surrounding formation, with conflicting ore richness. After some research, the general consensus is that the differing vein was altered by the hottest geothermal ore veins over the most aggressively folded zones. This greatly altered one of the central parallel veins while allowing the "flatter", surrounding veins to maintain similar geological makeups.

Manganoan calcite, also known as manganocalcite, is a pink, manganese-rich variety of calcite with a chemical composition of (Ca,Mn)CO3. It crystallizes in a trigonal crystal system and forms rhombohedral or scalenohedral crystals. These crystals tend to display a pink color that ranges anywhere from pinkish-salmon to hot pink. It often displays a bright orangey-pink fluorescence under short-wave UV light.