ORDEK I. GENERA AND SPECIES. 409 



2. PRISMATIC. Prismatic. P = 121 32', 108 35', 99 7'. 

 Cleavage, Pr + os. Pr + oo. Less distinct, P _ os. 



Traces of P + = 100 8'. 

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

 G. = 2-7 ... 3-0. 



Anhydrite. ii. 62. 



II. CRYONE-HALOIDE. Prismatic. 



Cleavage in three directions, perpendicular 

 to each other, one of them being more 

 distinct. 



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



G. = -9 ... 3-0. 



1. PRISMATIC. Prismatic. 



Cleavage, P co. Less distinct, Pr -f os. Pr + os 

 Traces of P. 



Cryolite. ii. 66. 



III. ALUM-HALOIDE. Rhombohedral. 



H. = 5-0. 



G. = 2-5 ... 2-8. 



1. RHOMBOHEDRAL. Rhombohedral. R = 92 50'. 

 Cleavage, R oo. Less distinct, R. 



Rhoniboidal Alumstone. J. ii. 67. 



IV. FLUOE-HALOIDE. Tessular, rhombohedral. 



H. = 4-0 ... 5-0. 

 G. = 3-0 ... 3-3. 



Rhombohedral : cleavage peritomous. 



1. OCTAHEDRAL. Tessular. 

 Cleavage, octahedron. 

 H. = 4-0. 

 G. = 3-0 ... 3-3. 



Fluor. 



