Ureyite, NaCrSi2O6: A New Meteoritic Pyroxene.
The new mineral NaCrSi(2)0(6) (ureyite) has been found as rareemeraldgreen grains in the iron meteorites Coahuila, Toluca, and Hex River Mountains. X-ray studies of the natural and synthetic material have established that the mineral is isostructural with jadeite, NaAlSi(2)0(6). Indexed data for powder patterns obtained by x-ray diffraction and precise cell dimensions are given for the Cr, Fe, and Al members of the jadeite group. Unlike jadeite, a high-pressure phase, ureyite can be synthesized from melts at 1-atmosphere pressure.
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