Diamond. 23 a. Oclacdron with bevilled edges, the bevilling planes cylindrically convex. b- Oftaedron with once broken bevilled edges. £• Odaedron with truncated edges, and the trun cating planes cylindrically convex. "When the bevilling planes of a become fo large as to caufe the planes of the odtaedron to difappear, an odtaedron is formed in which each plane is divided into tlnee, and the dividing edge runs from the middle point to the angles. ^ "When the planes of b increafe in the fame propor tion, every plane of the odtaedron becomes divided into fix, fo that three edges run from the middle point to the middle of the lateral edges, and three to the angles of the odaedron. as tn^V' 11 ^ truRcat ‘ n S pknes of c increafe fo much dnrW? 1 0ris ‘ nal ones to difappear, the garnet fori nV™-" g'^'-l-vcihtdal p,L ; s fo med Of t01s%llre lhe folw . ug va ,P. =s twin cryflals occur. When the planes of the acuminations very nearly touch each other, a double threc-fided pyra- nud is formed. 2 - Garnet dodecaedron with divided planes ; ir tms figure each plane is divided into two, and dividing edge pafTes through the obtuft an gic of the rhomb. 3. If two cryflals refembiing the preceding, bn with undivided planes, are turned around ; ixt 1 of their periphery, and pufhed into eacl ether, a very flat three-fided pyramid i formed
