Calcite
Calcite is one of the most important carbonate minerals. It is often referred to as a industrial mineral, and is found in over 300 forms. The photo is from the Southern California Deserts, is white. Calcite may be any color, from colorless to black, depending upon the other minerals contained in it. Calcite has a hardness of 3, SG of, and has a rhombohedral cleavage. .