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72 CHRYSOLITE FAMILY. which are imbedded, and so easily broken, that it is difj ficult to ascertain their form. Internally the lustre is shining and glistening, and is intermediate between resinous and vitreous. The fracture is small-grained uneven, sometimes pass ing into imperfect small conchoidal. The crystals have an imperfect foliated fracture, with a rectangular two fold cleavage, the folia being parallel with the lateral planes of the prism. The fragments are indeterminate angular, and rather 1 sharp-edged. The massive varieties occur in small and angulo-gra- nular concretions. It is translucent, passing into semi-transparent, seldom transparent. It is hard, but in a lower degree than chrysolite. It is brittle. It is easily frangible. Specific gravity, 3.225, Werner. 3.2C5, Klaproth. Chemical Characters. It is infusible before the blowpipe, without addition : with borax, it melts into a dark-green bead. It loses its colour in nitrous acid, the acid dissolving the iron, which is its colouring ingredient. Constituent Parts. Olivine of Unkel. Silica, - - 50.0 Magnesia, * 38.50 Lime, - 0.25 Oxide'of Iron, 12.00 100.75 Klaproth, Beit, b. v. s. 118. Gcognostio Olivine of Karlsberg. 52.00 37.75 0.12 10.75 100.62 Id. Klaproth, s. 121.