Plagioclase
From Antique Jewelry University
Plagioclase is a sub-series of the feldspar group.
Gemological information
| Gemological Information for Feldspar | |
|---|---|
| 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 |
| Similar Stones | Beryl, Quartz, Scapolite, Goldstone Glass |
| Treatments | Wax Impregnation, Irradiation |
| Country of Origin | Brazil, Madagascar, Norway, US, Russia |
| Feldspar 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.