PHYSIOGRAPHY". 



5. HHOMBOHEDRAL KOUPHONE-SPAR. 



Rhombohedral Zeolite, or Chabasite. JAM. Syst. Vol. I. 

 p. 359. Man. p. 145. Chabasie. PHILL. p. 138. Seha- 

 basit. WERN. Hoffin. H. B. II. 1. S. 257. Chabasin. 

 HAUSM. II. S. 585. Chabasie. LEONH. S. 449. Cha- 

 basie. HAUY. Traitt^, T. III. p. 176. Tabl. comp. p. 

 50. Trait^, 2de Ed. T. III. p. 163. 



Fundamental form. Rhombohedron. R = 94 46'. 

 Vol. I. Fig. 7. PHILLIPS. 



a = ^/ 3-538. 

 Simple forms. R 1 (n) = 125 13' ; II (P), 



Faroe; II + 1 (r) = 72 53'; P + oo (u). 

 Char, of Comb. Rhombohedral. 

 Combinations. 1. R 1. R. R -f 1. Fig. 120. 



Oberstein, Bavaria. 



2. R 1. R. R + 1. P 4- oo. The indivi- 

 duals in Fig. 173. Giant's Causeway, Ireland. 

 Cleavage, R 9 pretty distinct. Fracture uneven. 

 Surface, R 1 and P -f oo streaked parallel to 

 the edges of combination with R ; R -f 1 smooth. 

 The faces of R are generally streaked parallel to 

 their own terminal edges, which striae are pro- 

 duced by a scalene six-sided pyramid having ter- 

 minal edges of about 173J and 103 J, in paral- 

 lel position with R. 



Lustre vitreous. Colour white, little modified. 

 Streak white, Semi-transparent ... translucent. 

 Brittle. Hardness = 4-0 ... 4-5. Sp. Gr. = 2-100, 

 crystals from Bohemia. 



Compound Varieties, Twin-crystals. 1. Face 



