Calcite is a mineral found worldwide in limestone and marble. Large crystals and prismatic crystals are possible, but due to their softness, they are not faceted for jewelry. Marbles and limestone, rich with calcite, are used in carving and have a decorative value. Fine quality Italian marble is known worldwide for its beauty.
Gemological Information for Calcite
| Color: | Transparent, Colorless and most other colors |
| Crystal Structure: | Hexagonal (trigonal) |
| Refractive Index: | 1.486 to 1.658 |
| Durability: | Single Crystal=Poor Aggregates=Fair to Good |
| Hardness: | 3 |
| Family: | |
| Similar Stones: | Aragonite, Chalcedony, Coral, Alabaster |
| Treatments: | Dyeing, Impregnation with Wax and Plastic, Irradiation |
| Country of Origin: | Mexico, U.S. |
Calcite Care
| Ultrasonic Cleaning: | Never |
| Steam Cleaning: | Never |
| Warm Soapy Water: | Usually Safe |
| Chemical Attack: | Effervesces to Certain Acids |
| Light Sensitivity: | Natural Colors Stable |
| Heat Sensitivity: | Decrepitates at Higher Temps |
Sources
- Gem Reference Guide, Los Angeles: Gemological Institute of America, 1988. Pp. 41-43.
- Hall, Cally. Gemstones, Smithsonian Handbooks. London, DK Penguin Random House, 2021.
- Schumann, Walter. Gemstones of the World, New York: Sterling Publishing, Co., 1977. Pp. 208.