Calcite, a calcium carbonate with a hardness of 3, is one of the most abundant minerals on earth, occurring in a wide variety of forms and colors, including pink, blue, orange, yellow, and green. Clear calcite (also known as Iceland Spar or optical calcite) is a colorless, transparent variety which exhibits strong double refraction. When an image is viewed through a crystal, a double image will appear. Calcite makes up the major part of most marbles and limestone. Known for its cleansing, refreshing, and revitalizing influence, virtually all forms can heal with gentleness, and are good for moving beyond past patterns. Although calcite is found on every continent, some of the best crystal deposits are from Mexico, China, and the United States.