258 



PHYSIOGRAPHY. 



Vitreous Copper. 



o on o - 126 52' 



d on d 63 00 



o on o over c? 80 6 



Cleavage, traces of M, very imperfect. Fracture con- 

 choidal. Surface, most of the faces smooth, only the faces 

 at right angles to the axis, and particularly c, are streaked 

 horizontally. 



Lustre metallic. Color blackish lead grey. Streak un- 

 changed, sometimes shining. 



Very sectile. Hardness = 2*5 . . . 3-0. Sp. gr. = 5'695, 

 the compact variety from Bannat. 



Compound Varieties. Twin-crystals: 1. Axis of revo- 

 lution perpendicular to one or both faces of M ; face of 



Fig. 463. 



composition parallel to it, as in the accompanying figure, 

 only that the ra-entering angles are rilled up. 2. Axis of 

 revolution perpendicular, face of composition parallel to a 

 face of a ; the individuals being continued beyond the face 

 of composition. 



