For 10 points, name this mineral, the most stable form of calcium carbonate.
Bartholin was examining this material when he discovered birefringence. This chemical's namesake type of sea occurs during warming periods and predominated in the early Paleozoic and late Mezozoic. This mineral's hydrates include ikaite and it is polymorph of vaterite and aragonite. It exhibits three-fold perfect rhombohedral cleavage. A common component of limestone, it is the major constituent of marble. It is perhaps best known for its apperance in shells of marine animals. For 10 points, name this mineral, the most stable form of calcium carbonate.
Bartholin was examining this material when he discovered birefringence.
{calcite} [prompt on {calcium carbonate} or {CaCO}{3}]