Calcite
Mineral consisting of calcium carbonate. Next to quartz, it is the most abundant of earth's minerals. Crystallizing in a hexagonal system, calcite is known to exist in more than 300 crystalline forms. It also occurs in massive cryptocrystalline formations. Examples of the crystalline varieties are corn, spar, hog-tooth spar, nailhead spar, dogtooth spar, satin spar, and Iceland spar. The last named form is the only pure form of calcite found in nature. Limestone, chalk, and marble are among the most common of the massive forms of the mineral.
Calcite is also found as stalactites and calcareous tufas, forms deposited by mineral waters. Colorless, with a hardness of 3 and specific gravity 2.72, pure calcite is readily identified by the ease with which it is cut or cleaved and by the rapidity with which it reacts with dilute acids. Such contaminants as magnesium, ferrous iron, manganese, and zinc will alter the properties of the mineral in varying degrees, depending on the amounts present.
Magic & Myth
Calcite is said to be very beneficial for the cleansing organs, bones, joints, and for sharpening mental clarity. It helps boost the memory and softens the rigid boundaries of the intellectual mind so that true inner knowing can be attained. Calcite is recommended for those involved in the healing professions.