264 BORACITE FAMILY. Vauquelin found no lime in the transparent crystals, but only magnesia : hence he is of opinion, that boracite is a simple borate of magnesia. Nearly the same result was obtained by l’faff, in his analysis of the boracite of the Segeberg. Geognostic and Geographic Situations. This curious mineral has beet) hitherto found only in rocks ot gypsum in the Kalkberg, at Luneburg in Ha nover ; and also in the same formation, in the Segeberg, near Kiel in Holstein. Observations. 1. Lazius, who first attended to this mineral, named it Cubic Quartz: YVestrumb found by chemical analysis that it contained boracic acid and earths, and named it Seda- tive-spar; and Werner gave it its present denomination. 2. Fluor-spar is sometimes cut into the form of bora cite crystals, and sold as such to the ignorant. XXVI. BARYTE