Plagioclase is a sub-series of the feldspar group.
Gemological Information for Plagioclase
| Color: | Gray to Black for Labradorite, Yellow, Orange to Brown for Oligolcase |
| Crystal Structure: | Monoclinic |
| Refractive Index: | 1.599 to 1.568 Plagioclase |
| Durability: | Poor |
| Hardness: | 6 to 6.5 |
| Family: | Feldspar |
| Similar Stones: | Beryl, Quartz, Scapolite, Goldstone Glass |
| Treatments: | Wax Impregnation, Irradiation |
| Country of Origin: | Brazil, Madagascar, Norway, US, Russia |
Plagioclase Care
| Ultrasonic Cleaning: | Never |
| Steam Cleaning: | Never |
| Warm Soapy Water: | Safe |
| Chemical Attack: | Hydrofluoric Acid attacks quickly. Impurities may react to other acids. |
| Light Sensitivity: | Stable |
| Heat Sensitivity: | Can Crack, Fade and Cleave |
Sources
- Gem Reference Guide, Los Angeles: Gemological Institute of America, 1988. Pp. 101-107.
- Newman, Harold. An Illustrated Dictionary of Jewelry, New York: Thames and Hudson, 1981. Pp. 122.
- Schumann, Walter. Gemstones of the World, New York: Sterling Publishing, Co., 1977. Pp. 164-167.