gems, turquoise, Iran, Persia, Nishapur

Schindler describes the geology and mineral resources of the region between Sabzwâr and Meschhed (Mashhad), with particularly detailed attention to the famous turquoise mines of Nishapur. He states that the turquoise-bearing mountains consist principally of trachytic porphyries and breccias, together with diabase-like rocks, and that turquoise occurs only on their southern slopes. He lists numerous individual mines and describes their shafts, galleries, workings, and condition, noting that mining had continued there for thousands of years and that enormous underground cavities had resulted from the removal of ore and waste rock. The best turquoise was still obtained from the Abdurrezzâg mine; material in hard rock was darker and harder, whereas that in loose rock was lighter and softer. Schindler also describes five methods of recovering turquoise, including extraction directly from the host rock, recovery from old mine waste and rubble, and collection from alluvial deposits. He gives a valuable contemporary account of turquoise cutting and polishing and notes that most stones were only partly worked locally before being sent to Meschhed and thence through Russia into commerce. Of particular historical interest is his lengthy extract from a Persian mineralogy written by Muhammad ibn Mansur about 1300, which distinguishes turquoise from Nishapur, Ghazni, Transoxiana, Kerman, and Khwarazm, ranks seven varieties of Nishapur turquoise, discusses treatments and imitations, and records historical accounts of exceptionally large turquoise objects.