256 GYPSUM FAMILY. 75° 32and in which the terminal planes are set on ob liquely. The crystals occur singly, or in groups. The lateral planes are transversely streaked; the ter minal planes are smooth. It is shining. The fracture parallel with the terminal planes and edges is foliated ; in other directions it is conchoidal. It is softer than calcareous-spar. It is transparent. * * It is brittle. Specific gravity, 2.700. Chemical Characters. It decrepitates before the blowpipe, and melts into a white enamel. In water, it becomes opaque, and is part ly soluble. j Constituent Parts. Dry Sulphate of Lime, 49.0 Dry Sulphate of Soda, 51.0 100 0 Brongniart, J. des Mines, t. xxiii. p. 17. Geognostic and Gcographio Situations. It is found imbedded in rock-salt at Villaruba, near Ocana in New Castile, in Spain. Observations. It was brought from Spain to Paris by M Dumeril, and first analysed and described by Brongniart. XXV. boracitk
