Feldspar
Feldspar var. Moonstone.
Feldspar is a gem group that includes microcline, orthoclase, and plagioclase varieties. Each variety varies as to crystal structure, refractive index, color and other specifics. Gemstones include: amazonite, moonstone, labradorite, sunstone. From the Greek word klasis meaning cleaving (clase) with a cleavage direction as the prefix.
- Microcline
- Orthoclase
- Plagioclase
- Labradorite
- Oligoclase
- Spectrolite (trade name for Labradorite)
- Sunstone (variety of Labradorite or Oligoclase depending on the color)
Gemological Information for Feldspar
| Color: | Light Green, Greenish Blue, White for Microcline, Green, Colorless, White, Yellow, Brown, Gray and Black for Orthoclase, Gray to Black for Labradorite, Orange, Brown, Colorless for Oligoclase |
| Crystal Structure: | Triclinic (microcline) Monoclinic (orthoclase and plagioclase) |
| Refractive Index: | 1.522 to 1.530 (microcline) 1.518 to1.526(orthoclase) 1.599 to 1.568 Labradorite, 1.537 to 1.547 Oligoclase |
| Durability: | Poor |
| Hardness: | 6 to 6.5 |
| Family: | Feldspar |
| Similar Stones: | Aventurine Quartz, Chalcedony, Turquoise |
| Treatments: | Wax Impregnation, Irradiation |
| Country of Origin: | Worldwide Deposits |
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.