420 APPENDIX. Chemical Characters. It loses its colour before the blowpipe, and melts easily, and with intumescence, into a yellowish-green porous slag. Constituent Parts. Silica, ... 4.3 Alumina, - - . jg Lime, .... go Oxide of Iron, - - 16 Water, and other volatile mat ters, .... 4 99 Vauquclin, Journ. des Mines, N. 44. p. 571. Geognostic and Geographic Situations. It occurs in small layers, or in imbedded crystals, in primitive limestone, in the Pic Eres-Lids, near Bareges in France. Observations. 1. It was for some time considered as a variety of gar net, until Werner ascertained it to be a distinct sub stance, and placed it in the system between Leucite and Melanite, under its present name. 2. I am indebted to Mr Vivian for a description of this species. 2. Humite.