gems, turquoise, Iran, Persian turquoise

A short description is given of the history, the output and the geological conditions of the turquoise deposits of Nishabur, together with some remarks on the genesis of the deposits. Turquoise appears together with faustite, the zinc analogue of turquoise, opal, and sulphides in weathered intermediate volcanic rocks (among others: trachyte and trachyandesite). The rocks are stained and darkened by iron oxide, and are ascribed to the Tertiary Age. Also uranium minerals (autunite) have been found.