BORACITE, or BORATE OF MAGNESIA, in Mineralogy, occurs only in tessellar crystals, remarkably well defined. These are sometimes translucent, but generally opaque, and of a gray or a yellowish-white colour. Their specific gravity is equal to 2.974, and their contents, according to Pfaff, are, boracic acid 54.55, magnesia 30.68, oxide of iron 0.57, and silica 2.27. Boracite, before the blow-pipe upon charcoal, intumesces and melts into a glassy globule, which on cooling becomes white and opaque. It has hitherto been found only at Luneburg in Brunswick, and at Segeberg in Holstein, imbedded in compound varieties of gypsum and anhydrite.