MASAAKI OHMASA*, MASATOSHI SUZUKI and YOSHIO TAKEUCHI
Mineralogical Insti(ute, Faculty of Science,
University of Tokyo,
Hongo, Tokyo 113
ABSTRACT
The crystal structure of covellite has been refined, based on counter
intensity data, to R=3.9,°-6', using a crystal from Kosaka mine: P63/mmc,
a=3.976(1), c=16.382(5)'\, Z=6. The structure proposed by Oftedal (Zeits.
Krist., 83, 9-25, 1932) was confirmed. The S-S distance of the S2 groups in
the structure is 2.086(7)'\, the Cu-S distance in the CUS3 triangles 2.1915(4)'\,
and the mean Cu-S distances in the CUS4 tetrahedra 2.313'\. The highly
perfect cleavage characteristic of covellite may well be ascribed to the
strong Cu-S bonds in the CuS3 triangles which form, sharing corners, continuous
sheets parallel to (00l).
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