FOLIATED PREHNITE. 291 It occurs massive, and often also crystallised: the fol lowing are its crystallizations. 1- Oblique four-sided table, which is the fundamental figure, (fig. 70.) *. When this table increases in thickness, an oblique four-sided prism is formed. 2. The four-sided table is sometimes truncated, either on all its terminal edges, or only on the acute edges. When the truncations on ail the edges increase very much, there is formed 3. An unequiangular eight-sided table, (fig. 71.) "f*. When the truncations on the acute edges increase considerably, there is formed 4. An unequiangular six-sided table, (fig. 12 ) J. When these truncating planes increase in magnitude, and when the table at the same time becomes thicker, and the obtuse edges are slightly truncated, there is formed 5. A broad rectangular four-sided prism, rather flatly bevelled on the extremities, in which the bevelling planes arc set on the smaller lateral planes, and the edge of the bevelment is slightly truncated. "I he six-sided table sometimes becomes equilateral, a >'d forms, by superposition, an equilateral six- sided prism. , ^ 10 crystals are small and very small, seldom middle- sized. . ^ llc T seldom occur single, being generally aggregated, 111 such a way as to be attached by their lateral planes; s °inetitnes t!, bular and manipular groupes, sometimes T 2 iu * Prehnite rhomlraidalo, Hauy. + Prchnite octogonalc, Hauy. S Prclmite hexagonalc, llauy.
