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SPINEL. Sl it is brittle. Rather heavy, approaching to heavy. Specific gravity, 3.500, 3.789, Werner. 3.645, Ilauy. S.570, 3.590, IClaprolh. 3.705, Lowry. 3.523, Mohs. Chemical Characters. Before the blowpipe it is unalterable without addition ; but is fusible with borax. Constituent Parts. Alumina, - - 82.47 Magnesia, - - 8.79 Chromic acid, - - 6.18 Loss, ... 2.57 100 Vauquelin, J. M. N° 38. p. 8f*. Geognostic and Geographic Situations. It is found in the kingdom of Pegu, and at Cananor in the Mysore country; and in the island of Ceylon, ac companied with zircon, tourmaline, and ceylanite. It also occurs in drusy cavities along with vesuvian and cey lanite, &c.fin the granular ejected limestone of Vesuvius. We are still ignorant of the class of rocks in which it occurs. Werner conjectures that it may, like zircon and pyrope, be an inmate of floetz trap rocks *. Uses. * In the magnificent collection of the late Honourable Mr Greville, now in the British Museum, there are two interesting spucimens, which, although they do not enable us to ascertain the repository or kind of rock in which the spinel occurs, make us acquainted with some of its accompanying mine rals. In one of the specimens, crystals of spinel arc imbedded in calcare- otis-spar, and accompanied with crystals of mica, magnetic pyrites, and a aubstance which Count de Bournon believes to be aspuragus-stone; and in the other specimen, the spinel is imbedded in udularia, and is accompanied Witl» magnetic pyrites.