Structure refinements of beryl by single-crystal neutron and X-ray diffraction

Abstract

The crystal structure of beryl has been refined from single crystal neutron and x-ray diffraction data obtained on two samples with different alkali and H 2 O contents (morganite and aquamarine) in order to elucidate the ambiguities affecting the assignment of atomic species to the channel sites. Neutron data for morganite were obtained at 295 and 30K; neutron data for aquamarine and x-ray data for both samples were obtained at room temperature. The expected Li substitutions in the Be tetrahedral site and of Fe in the Al octahedral site were clearly confirmed by neutron data refinements