Photos by Amin Khosroshahi, ISNA
Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminum. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue. In recent times turquoise, like most other opaque gems, has been devalued by the introduction of treatments, imitations, and synthetics onto the market.
The substance has been known by many names, but the word turquoise was derived around the 16th century from the French language turquie, for Iranian material which was early imported through Turkey.
For at least 2,000 years, the region once known as Persia, has remained an important source of turquoise. This deposit, which is blue naturally, and turns green when heated due to dehydration, is restricted to a mine-riddled region in Neyshabur, the 2,012-metre (6,600 ft) mountain peak of Ali-Mersai, which is tens of kilometers from Mashhad, the capital of Razavi Khorasan province, Iran.
... Payvand News - 01/25/10 ... --