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534, ARSENIC. It occurs massive, disseminated, in membranes, reni- forra ; and crystallised in the following figures ; 1.- Oblique four-sided prism, flatly acuminated on the extremities with four planes, which are set on the acute lateral planes *, Fig. 263. 2. The preceding figure, truncated on the acute la teral edges +. 3. No. 1. truncated on all the lateral edges t, Fig. 264. 4. No. J. truncated on the obtuse lateral edges, and bevelled on the acute lateral edges §, Fig. 265. o. 1 he preceding figure, in which the edges formed by the meeting of the bevelling planes are trun cated ||, Fig. 266. 6. Oblique four-sided prism, acuminated with four planes, which are set on the lateral planes, and all the angles formed by the meeting of the acu minating and lateral planes, truncated Th(5 crystals are seldom middle-sized, usually small, very small and minute. The crystals are smooth, and frequently longitudinally streaked and shining, passing into splendent. Internally it is shining, and the lustre is intermediate between adamantine and resinous. I he fracture is coarse and small-grained uneven,' sometimes passing into imperfect conehoidal. T he fragments are indeterminate angular, and blunt- edged. ° It * Arser.ie sulphure rouge emousse, Hauy. t Arsenic sulphure rouge sexoctonal, Hauy. * Ar»enic sulphurs rouge dioctacdre, Hauy. § Arsenic sulphure rouge octodecima!, Ilaur. || Arsenic sulphure rouge octoduodecimal, Hauv. * Arsenic sulphure rouge surcoropose, Hauy.