Appearance
Unlike the original purple coloring of the traditional amethyst, green amethyst takes on a pale green color. Like most members of the quartz family, green amethyst is transparent. The stone also has a vitreous luster, or a smooth glassy sheen.
Chemical Composition and Crystal Structure
Green amethyst is made of one part silicon to two parts oxygen. The stone has a trigonal crystal structure. This means that there is one vertical three-fold axis, with four horizontal axes. Three of the four horizontal axes are equal, and the fourth is a different length and perpendicular to the others. Essentially, this means that there are three vertical planes to the stone and four horizontal planes. This affects how the stone can be cut and how stable various cuts will be.
Other Physical Properties
This stone has a hardness of seven on the Mohs scale of hardness. This means that the stone is relatively strong and can't be scratched by many other stones and minerals. Green amethyst has a relative density of 2.65. It also has a conchoidal, or shell-like, fracture. It has no cleavage, meaning that there is no line across which the stone will break naturally and smoothly.
Sources
Since green amethyst is derived from heating regular amethyst the sources are the same. Amethysts are found in Australia, Brazil, Canada, Germany, India, Madagascar, Mexico, South Africa, Sri Lanka, Uruguay and the United States.