Rhodochrosite, manganese carbonate, is associated with orebodies and occurs in spectacular crystals in a number of localities. Faceted gemstones are beautiful but too soft and fragile for use in jewelry. However, massive banded rhodochrosite occurs in a cave in Catamarca, Argentina. The formation is similar to a limestone cavern, complete with stalactites, stalagmites and thick 'flows', all made of pink manganese carbonate instead of the normal calcium carbonate. This banded material is widely used in jewelry as cabochons and ornamental objects. The stone pictured is about 3 inches across.