ORDER vi. AXOTOMOUS TRIPHANE-SPAR. 217 



Brittle. Hardness = 6-5 . ., 7-0. Sp. Gr. = 3 170, 

 a variety from Uton. 



Compound Varieties. Massive : composition gra- 

 nular, of various sizes of individuals, generally large. 



OBSERVATIONS. 



1. According to ARFVEDSON, the prismatic Triphane- 

 spar consists of 



Silica 06-40. 



Alumina 25-30. 



Lithia 8-85. 



Oxide of Iron 1-45. 



If exposed to a red heat, it loses transparency and colour. 

 Before the blowpipe it iutumesces, and then melts into a 

 nearly colourless transparent glass. 



2. It occurs in primitive rocks, massive, and engaged in 

 rhombohedral Quartz, along with rhombohedral Tourma- 

 line, prismatic Feld-spar, &c. 



3. It was first discovered at Uton in Siidermanland, 

 Sweden ; but has afterwards been found also at Sterzing 

 iji the Tyrol, and Killiney in Ireland. 



& AXOTGMOUS TRIPHANE-SPAK. 



Prismatic Prehnite. JAM. Syst. Vol. I. p. 338. Axoto- 

 mous Prehnite. Man. p. 136. Prehnite. PHILL. p. 36. 

 Prehnit. WERN. Hoffm. II. B. II. \. S. 220. Prehnit. 

 HAUSM. II. S. 560. Prehnit. L.EONII. S. 442. Preh- 

 nite. HAU Y. Traite', T. III. p. 167- Tabl. comp. p. 50. 

 Traite, 2de Ed. T. II. p. 603. 



Fundamental form. Scalene four- sided pyramid, 

 whose dimensions have not been exactly ascer- 

 tained. Vol. I. Fig. 9. 



Simple forms. P oo (P) ; P ; P + oo (M) 

 = 99 30 7 (nearly) ; Pr = 90 (nearly) ; Pr + oo 

 {&) ; f r + n (o) = 31 (nearly) ; ?r + oo (/). 



