1. The commoner, more stable, mineral form of calcium carbonate, CaCO3. It is the dominant component of all limestones and, due to its dissolution and reprecipitation by natural waters at normal temperatures, it is also the dominant mineral of chemical cave deposits including stalactites and stalagmites. It is white or colorless when pure but may be stained, most commonly to yellows and browns, by included impurities such as iron oxides. Its uninterrupted growth in a pool may allow development of good crystals, shaped as elongate scalenohedral pyramids of trigonal habit. Growth in stalactites and stalagmites is either in masses of fine parallel or radiating needles, or in a mosaic of larger rhombic crystals, easily identified by their well developed cleavage surfaces. Calcite is also the dominant vein mineral in limestones [9]. 2. A mineral composed of calcium carbonate (CaCO3) like aragonite but differing in crystal form; the principal constituent of limestone and other speleothems [10].