| Prasiolite | |
|---|---|
 | |
| General | |
| Category | Tectosilicateminerals,quartzvariety |
| Crystal system | Trigonal |
| Identification | |
| Color | Shades of green |
| Crystal habit | Hexagonal prisms |
| 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] |
| Ultravioletfluorescence | None |
Prasiolite (also known asgreen quartz, green amethyst orvermarine) is agreen variety ofquartz, with its color typically coming fromFe2+ ions within the crystal structure.[1][4]
Natural prasiolite is exceedingly rare, having been first discovered in the early 19th century inLower Silesia,Poland[5][6] with only a few other deposits known to exist. Natural prasiolite deposits includePłóczki Górne (Poland),Bahia (Brazil),Thunder Bay (Canada), and Farm Rooisand (Namibia).[6]
Nearly all commercially available prasiolite is artificial, either produced by heat-treatingamethysts from certain locations[7] to 400-500 °C,[8] orirradiating yellow-tinged quartzes.[9] Most amethyst will turn yellow or orange when heated, producing heat-treated amethysts which are often marketed ascitrine, but some amethyst will turn green when treated.[8] Significant prasiolite production began in the mid-1950s with the discovery that amethysts from the Montezuma mine inMinas Gerais, Brazil turned green when heat-treated.[10]
Most prasiolite sold is used injewellery settings, where it can substitute for far more expensivegemstones, such asperidot,tsavorite, andemerald.[11] Prasiolite used for jewelry comes from two main sources: heat-treated amethyst from the Montezuma mine, and irradiated yellow-tinged quartz from various locations throughout Brazil.[4]
Green quartz is sometimes incorrectly called green amethyst,[12] which is not an acceptable name for the material according toFederal Trade Commission Guidelines.[13] Other names for green quartz include vermarine and lime citrine.[14]
The word prasiolite literally means "leek-green stone" and is derived fromAncient Greekπράσονprason meaning "leek" andλίθοςlithos meaning "stone".[15][16] The stone was given its name due to its green-colored appearance.
Natural prasiolite is a very light, translucent green. Darker green quartz is generally the result of artificial treatment,[17] with lighter-colored prasiolite often irradiated with gamma rays as an attempt to obtain deeper colors.[18]
| Crystalline | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Cryptocrystalline | |||||||||
| Amorphous | |||||||||
| Miscellaneous | |||||||||
| Notable varieties |
| ||||||||
 | This article about a specificmineral ormineraloid is astub. You can help Wikipedia byexpanding it. |
