Polytypism of Heterogenite

M. Deliens and H. Goethals
Musée royal de l'Afrique centrale, Tervuren, Belgium
Laboratorium van Mineralogie, K.U.L., Leuven, Belgium

Summary: A new variety of heterogenite was found in samples from Mindigi, Shaba,1 Zaïre.2 Photometric reflectance varies from 0·235 to 0·165 at λ 5890 Å in air. The bireflectance is 0·070, the degree of anisotropy is 0·7 and the main index in air is 2·7. A thermal weight-loss curve and a microprobe analysis are given and discussed, indicating the formula (Co,Ni) O.OH.

The new variety, referred to as heterogenite-H, is hexagonal with cell dimensions a 2·85, c 8·80, space group P63/mmc and cell-content 2 [(Co, Ni)O.OH)]. Indexed X-ray powder data are given. A crystal structure is suggested based on CoO.OH octahedra layers and indicating a polytypic relation between heterogenite-H, the 2H form, and normal heterogenite, the 3R form.

1Shaba: new name since 1971 for Katanga. 2Zaïre: new name since 1971 for République Démocratique du Congo.

Mineralogical Magazine; June 1973 v. 39; no. 302; p. 152-157; DOI: 10.1180/minmag.1973.039.302.03
© 1973, The Mineralogical Society
Mineralogical Society (www.minersoc.org)