172 COPPER. latter passes into dark -blackish-green, verging on green ish-black. It occurs massive and disseminated. Internally it is shining and glistening, and the lustre is resinous. The fracture is small conchoidal. The fragments are indeterminate angular, and more or less sharp-edged. It is opaque. It becomes paler in the streak. It is soft, verging on very soft. It is rather brittle. It is easily frangible. It is rather heavy. Constituent Parts. According to Vauquelin, both subspecies of this mine ral are compounds of Oxide of Copper, Silica, and Wa ter. / Geognostic Situation. Both subspecies usually occur together, and they fre quently pass into each other. They are usually accom panied with copper-green, azure copper-ore, and mala chite; frequently also with grey copper-ore, foliated cop- per-glance, tile-ore, ochry and compact brown ironstone, compact red copper-ore, quartz, and straight lamellar heavy-spar, Geographic Situation. .Europe.—It occurs in Cornwall, along with oliven-ore; at Saalfeldt in 1 huringia, it is associated with malachite, azure copper-ore, copper-green, copper-pyrites, grey cop- pcr-ore,