Calcite (orange)

Orange calcite is a descriptive name for natural calcite (calcium carbonate, CaCO₃) of orange to orangy-yellow colour; it is a colour variety, not a separate mineral species. Gem laboratories have documented orangy-yellow calcite from Pakistan and Mexico and yellowish-orange calcite from the Czech Republic. The sources consulted do not establish a cause for the orange colour, and the Japanese retailer Pascle notes that the boundary with yellow calcite is not defined, so names vary between sellers.