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DIOPSIDE. 63 V It occurs massive, disseminated; and crystallised in the following figures: 1. I.ow, very slightly oblique four-sided prism, some times equilateral, sometimes broad. This is the fundamental or primitive form *. 2- The preceding figure truncated on the acute la teral edges, bevellec*on the obtuse edges, and the edge of the bevelment truncated : also rather acutely acuminated by four planes, two of the large acuminating planes set on the truncating planes of the acute lateral edges of the prism, the two smaller on the truncating planes of the bevelment. The two edges of the larger truncat ing planes, and the truncating planes ot the acute edges of the prism, and the apex of the acumi- nation, truncated. The broader lateral planes of the prism, and the truncating planes of the acumination, belong to the primitive form ■}*. 3. Eight-sided prism, with alternate broader and smaller lateral planes, acuminated with four planes, the acuminating planes set on the small er lateral planes, and this acumination again acuminated with four planes, set obliquely on the planes of the lower acumination, and of which two adjacent planes are large, and two small. The summit of the second acumination, and also the angles of the truncated summit, and the lateral edges of the larger planes, are trun cated. The smaller lateral planes of the prism, and the acuminating planes of the upper acumi nation, belong to the primitive form The * Diopside primitive, Hauy ; Mussite, Bonvoisin. "t Diopside didodecaedre, Hauy; Alalito, Bonvoisin, ? topside octovigcsimal, Ilauy.
