ORDEtt VII PRISMATIC TOPAZ. 309 



MONTEIRO. Denkschr. der Akad. der Wissensch. zu 

 Munchen. Jahr 1811 and 1812. S. 223. 



Fundamental form. Scalene four-sided pyramid. 

 P = 141 7, 101 52', 90 55'. Vol. I. Fig. 

 9. R. G. 



a : b : c = 1 : V 4-440 : V 1-238. 



Simple forms. P oo (P) ; P 1 = 155 37', 

 122 39', 53 5%' ; | P 1 (s) = 149 38', 

 120 32', 68 14' ; P (o) ; P + 1 = 130 27', 



74 39', 127 36'; P+ oo (M ) = 124 19'; 

 (4 p r _ i)5 (^ _ 123 o V9 126 o 18 / 5 82 o 8 / . 



(?r + QD) 3 (0 = 86 52'; (Pr + oo) 5 = 103 

 .14'; (P + oo) 5 = 64 31' ; Pr + 1 (ri) = 92 



59; Pr + 2 (y) = 55 34'; Pr + QD (r) ; 



Pr + 1 (e) = 58 11' ; Pr + QD = (/). 

 Char, of Comb. Prismatic. Some of the crystals 



shew different faces on opposite ends. 

 Combinations. 1. P. P + oo. (Pr + oc) 5 . Brazil. 



2. P. Pr-j-1. P+oo. (Pr+oo) 3 . Nert- 

 schinsk, Siberia. 



3. P. Pr+1. Pr+1. P + oo. (Pr+c/>) 3 . Peru. 



4. P 1. |P 1. (|Pr I) 3 . P. Pr+1. 

 P + oo. (Pr + a) 3 . Mucla, Asia Minor. 



5. P oo. I P 1. (|Pr I) 3 . P. Pr+1. 

 Pr + 2. P + x. (Pr + oo) 3 . Fig. 34. 

 Schneckenstein, Saxony. 



6. (I Pr I) 3 . P. Pr + 1. P+oo. (?r + oo) 3 . 

 Pr+1. P. Fig. 36. Brazil. 



Cleavage. P QD highly perfect ; ?r + 1 and Pr + 1 

 imperfect. Traces of P + oo and (Pr + oo) 5 par- 



