Huge, Apatite Crystals in Orange Calcite - Yates Mine, Quebec
These are apatite crystals in orange calcite that was collected from the Yates Mine in Quebec, Canada. The apatite crystals are olive-green and small amounts of purple fluorite can be found peppered throughout the calcite matrix. The longest apatite crystal is 5.75" long and the entire specimen measures 7.9 x 6.8".
Apatite's bright, lustrous crystals form hexagonal shapes with off-center terminations. They are found in vugs (small cavities in rock), often associated with quartz and calcite. Many crystals are around an inch in length, though larger crystals up to about 4 inches long have been found.
Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form.