RECENT X-RAY STRUCTURAL WORK ON SERPENTINE MINERALS By

and Zussman to be published fully in the Mineralogical Magazine during 1956. Part I describes work by Whittaker on the classification and characterization of chrysotile asbestos by means of x-ray fibre photographs. Part II, summarized here, describes the writer's work on powder photographs of various serpentine minerals, part of which makes use of Whittaker's results. Powder patterns were obtained from specimens of widely differing appear-ances which were seen to fall into three main groups. The first, consisting main-ly of specimens with splintery texture and with fibre axis repeat distance of 5.3 A gave the pattern of clinochrysotile alone, or of clinochrysotile mixed with a small percentage of orthochrysotile. All lines could be indexed on a basis of a cell with a = 5.32 A b ~ 9.2 ~ c = 14.64 A fl ~ 93020 ' (or fl = 90~ The second group gave patterns which could be indexed on the basis of a cell with a-- ~ 5.31 A b = 9.2 A c = 7.31 A fl z 90 ~ suggesting that they rep-resent a new structural variety of serpentine mineral in which single "sheet" units are stacked orthogonally. The observed relative intensities, however, ar