OBDEaxi. PRISMATIC MELAKE-GLAXCE. 7 



ralogists. It occurs in masses of considerable dimensions 

 in Cornwall, sometimes along with the di-prismatic Copper- 

 glance. In Hungary it is engaged in rhombohedral Lime- 

 haloide, but its locality is not exactly known. 



GENUS VIII. MELANE*-GLANCE. 

 1. PRISMATIC MELANE GLANCE. 



Rhomboidal Silver-Glance or Brittle Silver-Glance. JAM. 

 Syst Vol. III. p. 345. Prismatic Melane-G lance. 

 Man. p. 287. Brittle Sulphuret of Silver. PHILL. p. 

 390. Sprbdglaserz. WERN. Hoffm. H. B. III. 2. S. 

 63. Sprb'dglanzerz. HAUSM. I. S. 138. Schwarz- 

 giltigerz. LEONH. S. 202. Argent noir. HAUY. Traite, 

 T. III. p. 416. Argent antimonie' sulfure noir. TabL 

 comp. p. 76. Trait^ 2de Ed. T. III. p. 280. 



Fundamental form. Scalene four-sided pyramid. 

 P = 130 16', 104 19 7 , 96 T. Vol. I. Fig. 9. 

 R. G. 



a : b : c = 1 : V 2'526 : V M7- 



Simple forms. P OD ; P (P) ; P + oo = 111 

 8'; (Pr) 5 (a); (Pr -f a) 3 (d) = 72 13'; 

 (Pr -h oo)^ = 14S 10 7 ; (Pr) 5 ; Pr (o) = 115 

 39' ; Pr -f oo (p) ; Pr + oo (s). 

 Char, of Comb. Prismatic. 



1. Pr. Pr -f oo. Pr -f- oo. Alte Hoffnung mine, 



Freiberg 



^. P. (f r -f oo) 3 . Pr + oo. Fig. 7. Alte Hoff- 

 nung mine. 



3. Pr. P. (Pr) 5 . (Pr+oo) 5 . ]Pr + QD. Pr-f oo. 

 Fig. 30. Przibram, Bohemia. 



4. P oo. Pr. P. (Pr) 5 . (Pr) 5 . P + oo. 



* From pUa;, black. 



