GEOLOGY & PLANETARY SCIENCE A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site calcite Calcite. Credit: Mineral Information Institute A crystalline form of calcium carbonate (CaCO3). Calcite is one of the most common and widespread minerals. It crystallizes in the rhombohedral system, is usually colorless or white, and has a hardness of 3 on the Mho scale. It has the property of double refraction, which is apparent in the transparent variety of calcite known as Iceland spar. Calcite is an important rock-forming mineral and a major constituent of limestones, marbles, and carbonatites. Related category    • GEOLOGY AND PLANETARY SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP