Turquoise is a phosphate mineral. It is found in crevices along side deposits of copper, aluminum and sandstone, in arid regions of the world. The most signiicant deposits are found in Iran, the Sinai peninsula in Egypt and in the southwestern portion of the United States. It has a hardness rating of 6 making it just a little harder than ordinary glass. The stone color varies greatly. Stones vary in color from robin's egg blue to green to even a yellow-green. The blue stones are the most valuable. The black inclusions in the stone are deposits of malachite or limonite. In the United States this adds value where as in other countries a pure blue stone is more valuable. "Chalky" turquoise is found in the United States and is sometimes treated to make it more durable. Due to the softness of the stone, care must be taken when used in jewelry. Cleaning should be done with a damp cloth. Chemicals should never be used due to the stones porous nature. Be sure to protect the stone from makeup and hairspray. Store all turquoise jewelry separately to keep the stone from being damaged.