APOPHYLLlTE. 313 eight-sided prism; sometimes the eight solid angles of this figure are truncated. 4. The rectangular four-sided prism bevelled on all the edges, or only on some of them : sometimes one of the bevelling planes is awanting, when the edge appears to be only obliquely truncated. 5. Slightly oblique four sided prism. It is formed when the truncating planes of No. 3. become so large that the original planes disappear. 6. Rectangular four-sided prism, in which the angles are truncated, and the edges bevelled. 7. Rectangular four-sided table, in which the two op posite broader terminal planes are doubly bevel led, and the two smaller planes very flatly acu minated with four planes, of which two are set on the lateral planes, and the other two on the terminal planes, and the terminal edges bevelled. The crystals are very small, small, middle-sized, and Vor y rarely .large. The surface of the crystals Nos. 1, 2. and 4. is smooth; the surface of Nos. 3. and 5. and the acuminating planes of No. 7. arc longitudinally furrowed; the bevelling planes of Nos. 4. 6. and 7. are transversely streaked. All the other planes of the secondary crystals are smooth. Externally it is splendent; but only the terminal planes of the prism are pearly. The principal fracture is foliated, with a threefold cleavage: two of the cleavages are parallel with the lateral planes, and one with the terminal planes of a four sided prism. Traces of other indistinct cleavages are visible: the most distinct cleavage is that parallel with the ter minal planes, and which is splendent and pearly. 3 he cross fracture is small and perfect conchoidal, and the lustre is glistening and vitreous. The