408 Lead. 3- The octahedron, so deeply truncated on the sum' mits and the common base, that the original fa ces disappear, when there is formed a rectangu lar parallelopiped, which is either tabular, or in the form of a cuboidal prism *, as in fig, 244. 4. The octahedron, so deeply truncated on all the angles and on the cpmraon base, that the origi nal faces disappear, when there is formed a regu lar eight-sided table f, fig. 245. which is some times so thick as to appear as an eight-sided prism. 5. Octahedron truncated on the summits and com mon base, and bevelled on the angles of the common base, which gives rise to the rectangular four-sided table, bevelled on the terminal edges t, fig. 240. 0. Octahedron truncated on the lateral edges, which gives rise to the double eight sided pyramid. When this figure is deeply truncated on the sum mits, there is formed 7. A regular eight sided table, bevelled on the termi nal planes. The tables are usually broad and thin, and alternate rom sm all to very small, but are seldom middle sized. my are sometimes grown together, and frequently in tersect one another. Externally it is shining and smooth. nternallj it ls shining or glistening, and resinous in the foliated vaneties; but splendent and adamantine in those which are conchoidal. The * Plomb molybdate bis-unitaire, Hauy 4 Plomb molybdate tri-tinitaire, Hauy. •r Plomb molybdate pirioctogone, Hauy.