Vaterite is a mineral made up of calcium carbonate, with a chemical formula of CaCO3. It is one of the three forms of calcium carbonate, along with calcite and aragonite. Vaterite is commonly found in seashells and pearls, and has a trigonal crystal system. While vaterite is the most commonly used name for this mineral, it also goes by several synonyms. These include acmite, aloite, barcalite, bayerite, chalcedony, deshayesite, feldspar, kacolite, stephanite, and stichtite. Each of these names may refer to slightly different variations or forms of the mineral, but all share the basic chemical composition of calcium carbonate.