PHYSIOGRAPHY. 



Epistilbite. 



185 



Secondary forms. 



Fig. 171. 



Fig. 172. 



M 



M on t - - - - 122 9' 



t on * 109 46 



t on w 154 51 



t on 5 - - - - 141 47 



s on s 147 40 



Cleavage, perfect parallel with the shorter diagonal of 



the prism. In other directions only an uneven fracture. 



Surface, the faces M shining, but uneven, not admitting of 



the use of the reflective goniometer ; the faces s are dull ; 



t are smooth and shining. 



Lustre, on M vitreous ; that of r pearly. Color, white. 

 Transparent, to translucent on the edges. 

 Hardness ==4-5. Sp. gr. = 2-249 . . . 2-50. 



Fig. 173. 



Compound Varieties. Twin-crys- 

 tals : axis of revolution perpendicular : 

 face of composition parallel to one of 

 the primary lateral faces : angle of rev- 

 olution = 180. Massive : composi- 

 tion granular. 



16* 



M 



M 



