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318 ZEOLITE FAMILY. ^ The crystals arc small and very small, seldom middle- sized, and rarely large; and they are aggregated on one another, or mutually penetrate each other. The surface of the crystals is smooth, and splendent or shining. Internally it is intermediate between shining and glis tening, and the lustre is vitreous, inclining to pearly. The fracture is imperfect foliated, with a threefold cleavage, of which the folia are parallel with the sides of the cube. Owing to the imperfection of the foliated frac ture, it appears sometimes small or fine grained uneven. The fragments are generally indeterminate angular, seldom more or less cubical, owing to the imperfection of the foliated fractui'e. The massive varieties are disposed in coarse and small angulo-granular concretions, but which are very much grown together, and in general not very distinct. It is sometimes translucent, sometimes semi-trans parent, and in crystals is transparent. It is semi-hard, in a higher degree than zeolite. It scratches glass sensibly. It is easily frangible; and Rather heavy, inclining to light. Specific gravity 2.244, Vauqudin. Chemical Character. It melts before the blowpipe into a transparent glass. Physical Character. r* By rubbing, but not by heating, it becomes electric. Constitute
