Prasiolite is the green variety of Quartz. The material is extremely rare in nature and is only found in a handful deposits. The gem gets its name from the Greek prason meaning "leek" and lithos meaning "stone."

Most Prasiolite on the market has been created by heat treating amethyst of a certain composition or is synthesized. You will not find prasiolite in antique jewelry; the only known natural source that produces gem quality 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
Color	Green
Crystal Structure	Trigonal
Refractive Index	1.544-1.553
Family	Quartz
Durability	Excellent
Hardness	7
Similar stones	pale peridot, green beryl, green garnets
Treatments	Heat treatment
Country of origin	Brazil, Madagascar and Myanmar
Prasiolite care
Ultrasonic cleaning	Not safe
Steam cleaning	Not safe
Warm soapy water	Safe
Chemical attact	Usually safe
Light sensitivity	Stable
Heat sensitivity	Stable under normal conditions