Most Prasiolite on the market has been created by heat treating amethyst of a certain composition or has been synthesized. You will not find prasiolite in antique jewelry; the only known natural source that produces gem quality specimens is said to have been discovered in the 1950's in Brazil.
This 2009 paper speaks of irradiation causing some quartz to turn green.
|Gemological information for Prasiolite|
|Similar stones||pale peridot, green beryl, green garnets|
|Country of origin||Brazil, Madagascar and Myanmar|
|Ultrasonic cleaning||Not safe|
|Steam cleaning||Not safe|
|Warm soapy water||Safe|
|Chemical attact||Usually safe|
|Heat sensitivity||Stable under normal conditions|