Prasiolite, also known as green quartz or vermarine, is a green variety of quartz, a silicate mineral chemically silicon dioxide.
Since 1950, almost all natural prasiolite comes from a small Brazilian mine. We can also find it in Lower Silesia in Poland. And in the Thunder Bay area of Canada.
The major part of the stones are for jewelery. It can substitute for far more expensive precious gemstones.
It is a rare stone in nature. Heat treatment can artificially change the color of amethyst to become green. Most amethyst will turn yellow or orange when heated producing citrine. But some amethyst will turn green when treated. Currently, almost all stones on the market results from a combination of heat treatment and ionizing radiation.
Most gemstones dealer incorrectly talk about green amethyst, which is not an acceptable name for the material, the proper terminology being prasiolite. Other names for green quartz are vermarine, greened amethyst, or lime citrine.
Natural prasiolite is a very light, translucent green. Darker green quartz is generally the result of artificial treatment.
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. It is the second most abundant mineral in Earth’s continental crust, behind feldspar.
Quartz belongs to the trigonal crystal system. The ideal crystal shape is a six-sided prism terminating with six sided pyramids at each end. In nature quartz crystals are often twinned, with twin right handed and left-handed quartz crystals, distorted, or so intergrown with adjacent crystals of quartz or other minerals as to only show part of this shape, or to lack obvious crystal faces altogether and appear massive.
Well-formed crystals typically form in a bed that has unconstrained growth into a void, usually the crystals are attached at the other end to a matrix and only one termination pyramid is present.