Demantoid from Balochistan, Pakistan: Gemmological and Mineralogical Characterization

During the past few years, small demantoid crystals, indicated as coming from the Muslim Bagh area of Balochistan, have been available occasionally in the gem market in Peshawar, Pakistan. The gemmological properties and chemical data for this material are reported here. These bright green to yellowish green garnets are almost pure andradite (typically >=98 mol.%, with RI >1.79 and SG = 3.80-3.90). They contain inclusions of serpentine-group minerals, including the well-known fibrous 'horsetails', which are characteristic of a serpentinitic geological origin. Black crystals of Cr-rich magnetite are also common inclusions in demantoid from this relatively new locality. Iron and traces of chromium cause the green colour of these garnets.