Summary: New chemical, optical, and X-ray data have been obtained for dumortierite. The unit cell. space group Pemn, contains 4[(Al,Fe)7BSi3O18]. Brown gem quality material from Ceylon has α 1·6860, black, [001], β 1·722, deep redbrown, and γ, 1d7229, brown, with 2Vα 13° , γ > υ. X-ray powder data are given.
Mineralogical Magazine; September 1958 v. 31; no. 242; p. 901-907; DOI: 10.1180/minmag.1958.031.242.02
© 1958, The Mineralogical Society
Mineralogical Society (www.minersoc.org)