Polytypism in mcalpineite: a study of natural and synthetic CuTeO.

Synthetic and naturally occurring forms of tricopper orthotellurate, CuTeO (the mineral mcalpineite) have been investigated by 3D electron diffraction (3D ED), X-ray powder diffraction (XRPD), Raman and infrared (IR) spectroscopic measurements. As a result of the diffraction analyses, CuTeO is shown to occur in two polytypes. The higher-symmetric CuTeO-1C polytype is cubic, space group Ia3, with a = 9.

LiNaSiB3O7(OH)--novel structure of the new borosilicate mineral jadarite determined from laboratory powder diffraction data.

The structure of a new mineral jadarite, LiNaSiB(3)O(7)(OH) (IMA mineral 2006-36), has been determined by simulated annealing and Rietveld refinement of laboratory X-ray powder diffraction data. The structure contains a layer of corner-sharing, tetrahedrally coordinated Li, Si and B forming an unbranched vierer single layer, which is decorated with triangular BO(3) groups. The Na ion is situated between the tetrahedral layers in a distorted octahedral site.