jade, jadeite, fei cui, kaersutite, nephrite, gems

Three of four opaque black gems being represented in the trade as the pyroxene jadeite were identified by X-ray diffraction as rocks containing a maior component of amphibole, probably kaersutite. The fourth stone showed the diffraction pattern for jadeite. Since the basic gemnmological properties of some amphiboles like kaersutite overlap those of jadeite, routine gemmological testing cannot separate the two. More advanced testing techniques, such as X-ray diffraction and chemical analysis, are needed to make this separation.