Abstract
The rare mineral hureaulite was first discovered about 1825 by Alluaud1 on a few small specimens from Hureaux in the Department of Haute Vienne, France. The material was described by Dufrénoy2 and analyzed by him2a and by Vauquelin,3 the former making also a rough determination of the prism angle. Des Cloizeux4 found more material in a specimen of heterosite from La Vilate, near Chanteloube, in the same district, with crystals well enough developed to measure some of the forms with fair accuracy, and others by approximation. Hureaulite is also reported as probably occurring in Silesia. In the United States, hureaulite has been found at three localities only: Branchville5 and Portland, Conn.,6 and Pala, Calif.7 The Branchville material was fairly well crystallized, and measurements on it were much better than those of Des Cloizeaux, although according to the authors, not very accurate because of the multiple habit of the crystals. From these crystals the ordinarily accepted elements of crystallization were calculated.
