Details: This deposit is blue naturally and turns green when heated due to dehydration. It is restricted to a mine-riddled region in Nishapur, the 2,012-metre (6,601 ft) mountain peak of Ali-mersai which is tens of kilometers from Mashhad, the capital of Khorasan Province, Iran. A weathered and broken trachyte is host to the turquoise, which is found both in situ between layers of limonite and sandstone and amongst the scree at the mountain’s base. These workings are the oldest known, together with those of the Sinai Peninsula. Iran also has turquoise mines in Semnan and Kerman province.