Prasiolite, green quartz or vermarine is a green form of quartz, a silicate mineral chemically silicon dioxide. 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.
It is a rare stone in nature, so most of the prasiolite used today is lab created. Technically, prasiolite is heat treated amethyst. Most amethysts will turn yellow or orange when heated producing citrine, but some will turn green when treated. Currently most all prasiolite on the market results from a combination of heat treatment and ionizing radiation.
Other names for green quartz are vermarine, green 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."
Here is a photo of a silver ring with one big and two small prasiolites:
Check out more jewelry with prasiolite.