Color:
Turquoise, blues and greens

Sensitive to temperature: above 250 degrees C, a loss of water leads to a dull green color

Durability:
Fair

Localities:
Well known deposits occur in Persia, Sinai Peninsula, China, Chile, Egypt, Turkey, Mesoamerica (Arizona).

Turquoise
CuAlH₂0

Turquoise is a hydrous copper aluminum silicate, that occurs in microcrystalline nodules. Today, most turquoise has been "color stabilized", meaning it has been impregnated with wax, plastic resins, or sodium silicate, often with dye added. The use of turquoise dates back to 3000 B.C.- 4000 B.C.in the Sinai. It was the primary holy stone for Native Americans living in the Southwestern United States. Every Navajo carried a "personal" piece of turquoise. Middle Eastern tradition claimed that turquoise prevented accidents, especially falling. It was a talisman for horsemen, to keep them from falling off the horse. This belief carried over to Europe, evolving into the belief that if one did fall, no bones would be broken.

The Curious Lore of Precious Stones:
by George Frederick Kunz

Gemstone Buying Guide: A Guide to Buying
by Renee Newman