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76 CHRYSOLITE FAMILY* The crystals vary from acicular to the thickness of half an inch: they are frequently scopiformly aggregated, sometimes superimposed, and sometimes imbedded. The lateral planes of the crystals are longitudinally streaked. The lustre of the principal fracture is shining; that of the cross fracture glistening, and is semi-metallic. The principal fracture is small, and scopiform di verging radiated ; the cross fracture uneven. The fragments are indeterminate angular, rather sharp edged. . It occurs in thin and straight prismatic distinct con cretions. It is opaque. It is hard in a low degree: it scratches glass with ease, and gives a few sparks with steel, but is scratched by adularia. It does not change its colour in the streak. It is easily frangible. Specific gravity, 3.825, 4.061. Lelievre. Chemical Characters. It is attacked by the three mineral acids, but doc* not gelatinate with them. When exposed to heat, it be comes magnetic ; its colour is changed from black into dark reddish-brown, and it loses about 2 per cent, of weight. Before the blowpipe, it melts easily, and with out intumescence, into an opaque black grain, which ha* a dull metallic aspect, and is attracted by the magnet, but does not possess polarity. It dissolves in glass of borax, with a slight ebullition. Constituent