Prasiolite

Prasiolite (also known as green quartz, green amethyst or vermarine) is a green variety of quartz.

Not to be confused with Praseolite.

Prasiolite
General
Category	Tectosilicates, quartz variety
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]
Ultraviolet fluorescence	None

Since 1950, almost all natural prasiolite has come from a small Brazilian mine,^{[citation needed]} but it has also been mined in the Lower Silesia region of Poland. Naturally occurring prasiolite has also been found in the Thunder Bay area of Canada.^[4]

Prasiolite - Sokołowiec, Lower Silesia, Poland.

Most prasiolite sold is used in jewellery settings, where it can substitute for far more expensive precious gemstones.

Prasiolite is a rare stone in nature; artificial prasiolite is produced from amethyst.^[4] Most amethyst will turn yellow or orange when heated, producing heat-treated amethysts which are often marketed as citrine, but some amethyst will turn green when treated. Currently, almost all prasiolite on the market is made from amethyst via a process of heating and irradiation.^[5]

Green quartz is sometimes incorrectly called green amethyst,^[6] which is not an acceptable name for the material according to Federal Trade Commission Guidelines. Other names for green quartz include vermarine and lime citrine.^[7]

The word prasiolite literally means "scallion green-colored stone" and is derived from Greek πράσον prason meaning "leek" and λίθος lithos meaning "stone". The mineral 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.^[8]

See also

• List of minerals