38G PHYSIOGRAPHY". CLASS n. 



5. PRISMATOIDAL GARNET. 



Prismatic Garnet or Grenatite. JAM. Syst. Vol. I. p. 166. 

 Prismatoidal Garnet or Grenatite. Man. p. 229. Stau- 

 rolite. Grenatite. PHILL. p. 82. Staurolith. WERN. 

 Hoffin. H. B. I. S. 515. Staurolith. HAUSM. II. S. 

 629. Staurolith. LEONH. S. 424. Staurotide. HAUY. 

 Traite', T. III. p. 93. Tabl. comp. p. 43. Traite', 2de 

 Ed. T. II. p. 338. 



Fundamental form. Scalene four-sided pyramid. 

 P = 104 49', 99 22', 125 33'. Vol. I. Fig. 9. 

 HAUY. 



a : b : c = 1 : *J 0-5625 : J 0-5. 



Simple forms. P oo (P) ; Pr (r) = 70 32' ; 



(Pr + QD) 5 (M) = 129 31' ; r + oo (o). 

 Char, of Comb. Prismatic. 



Combinations. 1. P oo. (Pr-{- oo) 5 . Sebes, Tran- 

 sylvania. 



2. P oo. (Pr -f- oo) 5 . r + oo. Spain. 



3. P -oo. Pr. (Pr+<z>) 3 . f r + oo. Fig. 12. 

 St Gothard. 



Cleavage, Pr + oo perfect, but interrupted, traces 

 of (Pr + oo) 3 . Fracture conchoidal, uneven. 

 Surface, P GO sometimes very rough and cor- 

 roded, hollowed out in the centre. The rest of 

 the faces generally of the same quality, either 

 rough or smooth. 



Lustre vitreous, inclining to resinous. Colour red- 

 dish-brown, or brownish-red, very dark. Streak 

 white. Translucent, frequently only on the edges. 



Hardness = 7-0 ... 7-5. Sp. Gr. = 3-724, crystals 

 from St Gothard ; that of the common twin- 



