DESCLOIZITE  , a rare

mineral species consisting of basic lead and zinc vanadate, (Pb, Zn)2(OH)VO4, crystallizing in the orthorhombic system and isomorphous with olivenite . It was discovered by A: Damour in 1854, and named by him in honour of the French mineralogist Des Cloizeaux . It occurs as small prismatic or pyramidal crystals, usually forming drusy crusts and stalactitic aggregates; also as fibrous encrusting masses with a mammillary surface . The colour is deep cherry-red to brown or black, and the crystals are transparent or translucent with a greasy lustre; the streak is orange-yellow to brown; specific gravity 5.9 to 6.2; hardness 31 . A variety known as cuprodescloizite is dull green in colour; it contains a considerable amount of copper replacing zinc and some arsenic replacing Vanadium . Descloizite occurs in veins of lead ores in association with pyromorphite, vanadinite, wulfenite, &c . Localities arethe Sierra de Cordoba in Argentina, Lake Valley in Sierra county, New Mexico, Arizona, Phoenixville in Pennsylvania, and Kappel (Eisen-Kappel) near Klagenfurt in Carinthia . Other names which have been applied to this species are vanadite, tritochorite and ramirite; the uncertain vanadates eusynchite, araeoxene and dechenite are possibly identical with it .