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398 LEAD. 3. Six-sided prism, flatly acuminated on the extre* mities with six planes, which are set on the late ral planes * Fig. 237. 4. Regular six-sided prism, in which the terminal edges are truncated *(-. Fig. 238. 5. In acicular crystals, which are generally short and diverging. 1 he prisms are usually low, sometimes bulging, and hollow at their extremities. The crystals are small and very small, seldom middle- sized, and are often scalarwise aggregated. Externally it is smooth and shining, internally glisten ing, and the lustre is resinous. The fracture is small-grained uneven, passing on the one hand into yilintery, on the other into conchoidal. The fragments are indeterminate angular, and blunt- edged It is more or less translucent, seldom nearly transpa rent, and is sometimes only translucent on the edges. It is soft; it scratches white lead-ore. It is brittle. It 13 easily frangible. It is uncommonly heavy. Specific gravity, 6.560, from Wanlockhead, Klaproth. 6.270, Zschoppau, Klaproth. 6.9411, from the Ilreis- gaw, according to IIany. Chemical Characters. It dissohes in acids without effervescence. Before the blowpipe, on charcoal, it usually decrepitates, then melts, and on cooling, forms a polyhedral globule, the faces of which present concentric polygons: if this globule be pulverised, * I’iomb phosphate trihexaedre, Ilayy, t Plomb phosphate annulaire, Ilauy.