448 CHAllACTEllISTIC. CLASS II, 



1. TETRAHEDRAL. Semi-tessular with inclined faces. 



Cleavage, octahedron. 

 Colour steel-grey ... iron -black. 

 H. = 3-0 ... 4-0. 

 G. = 4-4 ... 5'2. 



Tetrahedral Copper-Glance. J. iii. 1. 



2. PRISMATOIDAL. Prismatic. 



Cleavage, ?r + GO. 



Colour blackish lead-grey. 



Brittle. 



H. = 3-0. 



G. = 5-7 ... 5-8. 



Prismatoidal Copper-Glance. J. iii. 4. 



3. DI-PRISMATIC. Prismatic. Pr 1 =87 8'; (r + oo) 3 



= 96 31'. 



Cleavage, Pr + oo. Pr + oo. The former rather 



more distinct. 



Colour steel-grey, inclining to lead-grey or iron-black. 

 Brittle. 



H. = 2-5 ... 3-0. 

 G. = 5-7 ... 5-8. 



Bournonite. iii. 5. 



4. PRISMATIC. Prismatic. r = 119 35'; (Pr + oo) 3 = 



63 48'. 



Cleavage, Pr, very imperfect. 

 Colour blackish lead-grey. 

 Very sectile. 

 H. = 2-5 ... 3-0. 

 G. = 5-5 ... 5-8. 



Prismatic Copper-Glance or Vitreous Copper. J. iii. 8. 



II. SILVER-GLANCE. Tessular. 

 Colour blackish lead-grey. 

 H. = 2-0 ... 2-5. 

 G. =6-9 ... 7-2. 



