236 PHYSIOGRAPHY. CLASS 11. 



hedral Lime-haloide. Along with the same species it is 

 likewise found in irregular veins and imbedded masses in 

 porphyry, and in the cavities of amygdaloidal rocks. 



3. The first variety noticed of this species Avas discovered 

 by GILLET LAUMONT, in the lead mines of Huelgoet in 

 Brittany, and has received its name in compliment to the 

 discoverer. It was afterwards found near Schemnitz in 

 Hungary in porphyry. It occurs likewise in Mount St 

 Gothard with rhombohedral Fluor-haloide, in Faroe, Ice- 

 land, and various parts of Scotland and Ireland. 



7. PRISMATIC KOUPHONE-SPAll. 



Prismatic Zeolite or Mesotype. JAM. Syst. Vol. I. p. 368. 

 Man. p. 146. Mesotype. PHILL. p. 123. Faserzeo- 

 lith (in part). WERN. Hoffm. H. B. II. 1. S. 233. 

 Zeolith (in part). HAUSM. II. S. 564. Mesotyp (in 

 part). LEONH. S. 452. Mesotype. HAU Y. Traite', T. III. 

 p. 151. Tabl. comp. p. 48. Traite, 2de Ed. T. III. p. 179. 



Fundamental form. Scalene four-sided pyramid. 

 P = 142 20', 142 40', 53 20'. Vol. I. Fig. 9. 

 R. G. 



a : b : c = I : V 8 '7 : A/7'794. 



Simple forms. P (o) ; P + oo (Jf ) = 91 0' ; 



Pr + oo (r). 



Char, of Comb. Prismatic. Combination. P. P -j- oo. 

 Cleavage, P -f- oo, perfect. Fracture conchoidal, 



uneven. Surface, Pr -f oo, vertically streaked, 



the rest of the faces smooth. 

 Lustre vitreous. Colour, few shades of white, 



generally greyish, Streak white. Transparent . . . 



translucent. 

 Brittle. Hardness = 5-0 ... 5-5. Sp. Gr. = 2-249. 



Compound Varieties. Implanted globular shapes : 



