ORDER XI. IIEXAHEDKAL LEAD-GLAKCE. 13 



4. The hexahedral Silver-glance is an important species 

 for the extraction of silver. 



GENUS III. LEAD-GLANCE. 

 1. HEXAHEDRAL LEAD-GLANCE. 



Hexahedral Galena or Lead-glance. JAM. Svst. Vol. III. 

 p. 353. Man. p. 280. Galena. Sulphuret of Lead. Blue 

 Lead. PHILL. p. 332. 335. Bleiglanz. Blau-Bleierz. 

 WERN. Hoffm. H. B. IV. 1. S. 1. 13. Bleischweif. 

 Bleiglanz. HAUSM. I. S. 178. 179. Bleiglanz. LEONH. 

 S. 225. Plomb sulfure'. HAUY. Traite', T. III. p. 

 456. Tabl. comp. p. 79. Traite', 2de Ed. T. III. p. 341. 



Fundamental form. Hexahedron. Vol. I. Fig. 1. 



Simple forms. H (P), Freiberg ; 6 (e) Vol. I. 

 Fig. 2., Bleiberg; D (o) Vol. I. Fig. 31.; B (/) 

 Vol. I. Fig. 33. ; C 2 (z) Vol. I. Fig. 34. 



Char, of Comb. Tessular. 



Combinations. 1. H. O., Vol. I. Fig. 3. and 4. Al- 

 ston, Cumberland. 



2. H. O. D. Pfaffenberg mine, Anhalt. 



3. H. O, Ca. Przibram, Bohemia. 



4. H. O. D. B. Fig. 155. Feistritz, Stiria. 

 Cleavage, hexahedron, highly perfect, and easily 



obtained. Fracture conchoidal, seldom observ r - 

 able. Surface, the hexahedron and the trigonal- 

 icositetrahedron streaked parallel to the edges of 

 combination with the octahedron. Sometimes 

 subject to tarnish.* 



Mr ALLAN first observed, in several specimens in his own 

 cabinet, that, in some combinations of the hexahedron with the 

 octahedron from Alston, the faces of the octahedron are tar- 

 nished, and present iridescent tints, while those of the hexahe- 

 dron have retained their original lead-grey colour. H. 



