Artificially Induced Color in Amethyst-Citrine Quartz

Adjacent amethyst and cltrine colors in the same crystal of quartz have been reported from So~rrh Arnerica, although there appears to be uncertainty as to the exact locality of origin. Such material has also been prodr~ced by synthesis. Several previous studies on the imp~~ri t ies contained in natural and synthetic quartz and the effects of irrndiation and heating, as well as new heating and Irradiation experiments with the current natural amethyst-citrine quartz and with amethyst, are described. It is concluded that there are presently no lznown tests to distinguish natural blcolor material that wns heated or irrudiated (or both) in nnture from natural amethyst heated or irradiated (or both) by man or from the ecluivaient synthetic material.