CHRYSOLITE. 67 planes, two are set on the broader lateral planes, and the other four on the truncating planes ot the lateral edges. The apex of the prism is truncated *, tig. 119. f. 2. The preceding figure, but acuminated with eight planes, which are set on the lateral and truncat ing planes of the prism, and the apex of the prism deeply truncated, fig. 120. 3. The preceding figure, in which the edge between the truncating plane of the apex of the acumina- - tion, and the acuminating plane which rests on the smaller lateral plane, is truncated, fig. 121. ||. 4. Very oblique four-sided prism, in which the acuter edges are bevelled, and the edges of the bevel- ment truncated; and acuminated on the ex tremities with four planes, which are set on the lateral edges, and the apex of the acu- mination slightly truncated. This figure is formed from N° 1. when the truncations on the lateral edges increase, until the broader lateral planes disappear. Sometimes the bevelling and acuminating planes are very small, but the trun cating planes of the hevelment large, so that the crystal appears like a four-sided table of heavy- spar, bevelled on the terminal planes, or it as sumes a reed-like aspect, §, fig. 122. £ 2 5. Less * The primitive form, according to Hauy, is a four-sided prism, with rectangular bases. Tbe cleavage of the smaller lateral planes pretty dis. tinct, the others indistinct. t Peridot triunitaire. Hauy. i Peridot monostiquc, Hauy. II Peridot subdistique, Hauy. * § Peridot continu, Hauy.