Prasiolite or vermarine is a green-colored form of quartz, usually produced by artificially heat-treating amethyst. Since 1950, almost all has come from one small mine in Brazil. Natural prasiolite has also been obeserved in Lower Silesia in Poland. The gem has a refractive index of about 1.54-1.553.[http://ist-socrates.berkeley.edu/~eps2/wisc/ri.html

Gemstones | Quartz varieties | prásio