Prasiolite
| Prasiolite (quartz variety) | |
|---|---|
|
Raw natural prasiolite | |
| General | |
| Category | Oxide mineral |
| Identification | |
| Color | shades of green |
| Crystal habit | Hexagonal prisms |
| Crystal system | Trigonal |
| Cleavage | None |
| Fracture | Conchoidal[1] |
| Tenacity | brittle[1] |
| Mohs scale hardness | 7 – lower in impure varieties[1] |
| Diaphaneity | Transparent to nearly opaque |
| Specific gravity | 2.65 |
| Refractive index | 1.544 to 1.553[2] |
| Birefringence | 0.009[3] |
| Ultraviolet fluorescence | none |
Prasiolite, green-quartz or vermarine is a green form of quartz, a silicate mineral chemically silicon dioxide. Prasiolite is one of several quartz varieties. Since 1950, almost all natural prasiolite has come from a small Brazilian mine, but it is also seen in Lower Silesia in Poland. Naturally occurring prasiolite is also found in the Thunder Bay area of Canada.[4]
Prasiolite can also be found spelled praziolite. Prasiolite can be confused with the similarly colored praseolite which results from the heat treatment of iolite, a variety of cordierite.[5] Most prasiolite sold is used in jewellery settings.
It is a rare stone in nature; artificially produced Prasiolite is heat treated amethyst.[4] Most amethyst will turn yellow or orange when heated producing citrine. But some amethyst will turn green when treated. Currently, almost all prasiolite on the market results from a combination of heat treatment and ionizing radiation.[6]
Green quartz is sometimes incorrectly called green amethyst, which is an actual misnomer and not an acceptable name for the material, the proper terminology being Prasiolite.[7] It is actually against Federal Trade Commission Guidelines to call prasiolite "green amethyst." Other names for green quartz are vermarine, greened amethyst, or lime citrine.
The name is derived from Greek πράσον prason meaning "leek" and λίθος lithos meaning "stone." This means that "prasiolite" literally means "scallion green-colored stone." The mineral was given its name due to its green-colored appearance.
See also
References
- 1 2 3 Prasiolite on Gemdat.org
- ↑ Lazarelli. Blue Chart Gem Identification. p. 7.
- ↑ http://www.galleries.com/Prasiolite
- 1 2 "Prasiolite". quarzpage.de. 28 October 2009. Retrieved 28 November 2010.
- ↑ "Prasiolite". Amethyst Galleries' Mineral Gallery.
- ↑ "Mineral Spectroscopy Server". California Institute of Technology. 11 June 2012. Retrieved 10 December 2012.
- ↑ "Green Amethyst". GemSelect. Retrieved 10 December 2012.
External links
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||||||