ORDER vi. PRISM ATOIDAL KOU PHONE-SPAR. 239 



varieties of Natrolite occur in veins traversing clinkstone, 

 others in amygdaloid. 



4. The variety of Mesotype, to which the preceding ge- 

 neral description refers, is found in several localities near 

 Clermont-Ferrand in Auvergne. Other varieties occur in 

 Iceland, the Faroe islands, Tyrol, Italy, the Lipari islands, 

 &c. ; the Natrolite is met with at Hohentwiel in Swabia, 

 and at Bilin in Bohemia, some varieties of it also in the 

 valley of Fassa in Tyrol, &c. 



8. PRISM ATOIDAL KOUPHONE-SPAR. 



Prismatoidal Zeolite or Stilbite (Radiated Zeolite). JAM. 

 Syst. Vol. I. p. 378. Man. p. 149. Stilbite. PHILL. 

 p. 37. Strahlzeolith. WERST. Hoffm. H. B. II. 1. S. 

 237. Blattrich-strahliger. Stilbit. HAUSM. II. S. 575. 

 Stilbit (in part). LEONH. S. 445. Stilbite (in part). 

 HAUY. Traite', T. III. p. 161. Tabl. comp. p. 48. 

 Traite', 2de Ed. T. III. p. 155. 

 BROOKE, Edin. Phil. Journ. Vol. VI. p. 112. 



Fundamental form. Scalene four-sided pyramid. 

 P = 11915',114 0',960'. Vol. I. Fig. a BROOKE. 



a : b : c = 1 : V 1-7502 : V 1-5087. 



Simple forms. P oo (P) ; P (r) ; P + oo = 



94 15'. Pr + oo (T) ; Pr + QD (M). 

 Char of Comb. Prismatic. 

 Combinations. 1. P. Pr + oo. Pr -f oo. Iceland. 



2. P cc. P. Pr -f oo. Pr + x. Fig. 10. Faroe. 



3. P oo. P. P + oo. Pr + x. Pr + oo. Camp- 

 sie, Stirlingshire. 



Cleavage, Pr + CD highly perfect, traces of Pr + oo. 

 Fracture uneven. Surface, P oo often curv- 

 ed, Pr -f- oo vertically streaked, still more so 

 Pr + QD. 



Lustre vitreous. The faces Pr 4- oo, both as fa- 



