Pharmacolite

Pharmacolite is a calcium arsenate hydrate mineral that forms as a secondary phase in oxidized zones of arsenic-rich environments. It typically crystallizes as small, tabular to platy crystals, often with a vitreous to pearly luster and a pale to colorless to light blue-green color that can be quite delicate. The mineral commonly occurs in association with other arsenates and phosphates, reflecting its formation under relatively dry, low-temperature conditions near hydrothermal or supergene environments. Chile is a well-known source for Pharmacolite specimens, where oxidized pockets and neuropathic arid terrains yield small, well-formed crystals that are prized by collectors for their subtle coloration and crystal habit. Collectors value Pharmacolite for its rarity in many localities and the challenge of finding well-preserved, sharp faces with clean termination, often showcased in small crystals within matrix or vug-like cavities.