402 FELSPAR FAMILY. with the terminal planes «f the prism ; the cross fracture is eonchoidal. The fragments are sharp-edged. It is strongly translucent, passing into transparent. It is hard in a low degree ; its sharp corners scratch glass. It is rather heavy, but in a middling degree. Specific gravity, 2.214, Hauy. Chemical Characters. It is not soluble in nitrous acid; but transparent pieces, when immersed in that acid, become cloudy in the interior: hence the name Nepheline, from a cloud, given to this species by Ilauy. It melts with dif ficulty before the blowpipe into a dark glass. Constituent Parts. Silica, - - . 46 Alumina, - - 49 Lime, - o Oxide of Iron, - . i 98 Vauquelin> Geognostic and Geographic Situations. It occurs in drusy cavities in granular limestone, along with ceylanite, vesuvian, and meionite, at Monte Sonnna, near Naples; also in fissures of basalt at Capo di Cove, near ltome. It is mentioned also as a production of the Isle of Bourbon, Observations. 1. This species is characterised by its white colours* which sometimes incline to green, its crystallizations, vitreous
