OKDER XIII. GENERA AND SPECIES. 453 



2. HEMI-PRISMATIC. Hemi-prismatic. P + co = 8C 4'. 



Inclination of P co on the acute edge = 101 6'. 



Cleavage, 1 1 !"_ and Pr + co, imperfect. 



Streak dark cherry-red. 

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

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



Var. of Dark Red Silver. Vulg. Hi. 42. 



3. PER'ITOMOUS. Rhombohedral. 11 = 71 47'- 



Cleavage, 11 + co, highly perfect. 

 Streak scarlet-red. 

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

 G. = 6-7 ... 8-2. 



Cinnabar. iii. 44. 



XIII. ORDER. SULFUR, 



I, SULPHUR. Prismatic. 

 H. = 1-5 ... 2-5. 

 G. = 1-9 ... 3-6. 



1. PRISMATOTDAL. Prismatic. Pr = 83 37'. P + co 



= 117 49'. 



Cleavage, Pr -f co, eminent- 

 Streak lemon-yellow. 

 H. = 1-5 ... 2-0. 

 G. = 3-4 ... 3-6. 



Orpiment. iii. 47. 



p 



2. HEMI-PRISMATIC. Hemi-prismatic. = 130 0. 



Inclination = 4 I'. 

 leavage, ?!L = 6U 

 P -f co = 74 30'. Pr -f co. Imperfect. 



Cleavage, = 60 44'. Pr + co. Less distinct, 



