Investigation of the crystal structure of antigorite

Abstract

Selfridge (1936) examined by chemical, optical, and X-ray powder methods a large number of specimens of serpentine minerals (ideal formula H4Mg3Si2O9), many of which were known as antigorite. He found that nearly all gave similar powder photographs, indicating a close structural relationship, but that there were noticeable differences on the basis of which the specimens could be separated into two groups, one giving a photograph similar to that of chrysotile asbestos, and the other containing the varieties called antigorite. Gruner (1937) came to similar conclusions, and in addition he indexed most of the reflections using the cell dimensions a 5.33, b 18.5, c 2 x 7.33 Å., β 93°, remarking in particular on the correspondence between 001 reflections in the two groups.