THE NATURAL ARRANGEMENT. XXIX 



Gen. III. TUNGSTIC BARYTE. (M.) H. 4'0...5'5. 



G. 4'5... 6'J. 

 Sp. 1. Pyramidal 29 (M.) Tungsten. 



2. P r i s m a t i c (S.) Xenotime. 3 (BEU.) 



3. O c t a h e d r a 1 (S.) Microlite. (S.) 



4. Perilomous (S.) Thorite. 



5. Rhombohedral (S.) Flucerine. 



6. Tetarto-prismatic(S.).M0tta:^e. (B.) 



Gen. IV. HAL-BARYTE. (M.) Prismatic and hemi-pris- 



matic. H. 3 ... 4*0. G. 3'6 . . . 4'7. 



Sp. 1. P e r i t o m o u s (M.) Strontianite. 



2. Hem i-p r i s m a t i c (M.) Baryto- Calcite. 



3. D i-p r i s m a l i c 3 1 ' (M.) Witherite. 



4. Prismatic (M.) Heavy Spar. 



5. Prisrnatoi d al (M.) Celestine. 



Gen. V. LEAD-BARYTE. (M.) H. 2'5...4'0. G. 54 



...7-3. 



Sp. 1. P e r i t o m o u s i^M.) Kerasite. 



2. K e r a s i n e (S.) Corneous Lead. 



3. D i-p r i s in a i i c (M.) White Lead Ore. 



29 Applied to crystals derived from the riglit square 

 prism, and from the octahedron with a square base. 



30 Ksvos, vain, and TIJULTJ, honor; in allusion to the cir- 

 cumstance that the phosphate of yttria, of which this mine- 

 ral consists, was for a time regarded as the oxide of a new 

 metal, the Thorium. 



31 When the cleavages are parallel to the sides of a four- 

 sided vertical prism, and at the same time to a horizontal 

 prism. 



D 



