Prasiolite

Vermarine (quartz variety)
Raw natural vermarine
General
Category	Oxide mineral
Crystal system	Trigonal
Identification
Color	shades of green
Crystal habit	Hexagonal prisms
Cleavage	None
Fracture	Conchoidal
Tenacity	brittle
Mohs scale hardness	7 – lower in impure varieties
Diaphaneity	Transparent to nearly opaque
Specific gravity	2.65
Refractive index	1.544 to 1.553
Birefringence	0.009
Ultraviolet fluorescence	none

Vermarine, green quartz or prasiolite is a green form of quartz, a silicate mineral chemically silicon dioxide. Vermarine is one of several quartz varieties.

Since 1950, almost all natural vermarine has come from a small Brazilian mine, but it is also seen in Lower Silesia in Poland. Naturally occurring vermarine is also found in the Thunder Bay area of Canada.

The term prasiolite is also rarely found as praziolite. Prasiolite can be confused with the similarly colored praseolite which results from the heat treatment of iolite, a variety of cordierite. Most vermarine sold is used in jewellery settings, where it can substitute for far more expensive precious gemstones.

It is a rare stone in nature; artificially produced vermarine is heat treated amethyst. Most amethyst will turn yellow or orange when heated producing citrine. But some amethyst will turn green when treated. Currently, almost all vermarine on the market results from a combination of heat treatment and ionizing radiation.

Green quartz is sometimes incorrectly called green amethyst, which is not an acceptable name for the material, the proper terminology being prasiolite. It is actually against Federal Trade Commission Guidelines to call vermarine "green amethyst." Other names for green quartz are vermarine, greened amethyst, or lime citrine.

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.