74 SCHORL FAMILY. the lateral edges, as fig. 35.; truncated on the terminal angles as in fig. 36.; or on the terminal edges and angles as in fig. 37. The truncations on the terminal edges sometimes be come so large as to form six-planed acuminations, in which the apices appear deeply truncated, as in fig. 37. The lateral planes are deeply longitudinally streaked, but the terminal acuminating and truncating planes are smooth. The lateral planes vary much in breadth; sometimes three planes are so large in comparison of the others, that the crystal appears almost trihedral: in other instances, four planes are so large, that the figure is almost tetrahedral. Sometimes the lateral planes are cylindrical convex, and then the crystals appear acicular or reed-like. The crystals are sometimes jointed like basalt, having a concave surface at one extremity, and a convex surface at the other. They are seldom single; generally many occur together, and these cross each other in different directions, and are frequently superimposed and imbed ded. The crystals are small, large, and very large. Transparent crystals occur a foot long, and four inches in diameter *. Externally its lustre is shining and glistening ; inter nally shining, which sometimes .passes into glistening and splendent, and is vitreous. The • In Weiss’s collection in Vienna there is a druse of very large baryl cry stals ; two of the crystals, which are of a mountain-green colour, and cross each other, are a foot and a half long, and one foot in diameter.