Scientific Name: Lead chromate
Chemical composition: PbCrO4
Colors: Orange, red
Hardness: 2.5 to 3
Formation: Monoclinic crystal; prismatic form; cleavage distinct in one direction; conchoidal to uneven, brittle fracture; vitreous luster; transparent to translucent
Principal Sources: Tasmania; Russia; Germany; California, USA
Special Notes: Crocoite is sometimes used as a paint, being identical in composition with the artificial product chrome yellow. It takes its name from the Greek for “saffron” after its color. The relative rarity of crocoite is connected with specific conditions required for its formation: an oxidation zone of lead ore bed and presence of ultramafic rocks serving as the source of chromium (in chromite). Oxidation of Cr3+ into CrO42- (from chromite) and decomposition of galena (or other primary lead minerals) are required for crocoite formation.