1C PHYSIOGRAPHY. CLASS II. 



Fine crystals have been obtained from the Pfaffenberg 

 mine near Neudorf in Anhalt, from Saxony, from Transyl- 

 vania, from Cumberland and Durham, &c. Compact Lead- 

 glance chiefly occurs at Freiberg in Saxony, in the Hartz, 

 in Carinthia, and at Leadhills in Scotland. The localities 

 of Blue Lead have been mentioned above. 



5. Hexahedral Lead-glance is that mineral which yields 

 most of the lead annually produced. On account of its 

 generally containing a small quantity of silver, it is also 

 employed to a considerable extent for the extraction of that 

 metal, or also of gold, if it contains an admixture of it, 

 which is sometimes the case. Potters use either the hexa- 

 hedral Lead-glance itself reduced to powder, or the litharge 

 produced from it for glazing coarse pottery. 



GENUS IV. TELLURIUM-GLANCE. 



1. PRISMATIC TELLURIUM-GLANCE. 



Prismatic Black Tellurium. JAM. Syst. Vol. III. p. 369. 

 Prismatic Tellurium-Glance. Man. p. 281. Black Tel- 

 lurium. PHILL. p. 328. Nagyager-Erz. WE UN. Hoffin. 

 H. B. IV. 1. S. 134. Bliittertellur. HAUSM. I. S. 132. 

 Blatter-Tellur. LEONH. S. 182. Tellure natif auri- 

 fere et plombifere. HAur. Traite', T. IV. p. 327. 

 Tellure natif auro-plombifere. Tabl. comp. p. 119. 

 Traite', 2de Ed. T. IV. p. 381. 



Fundamental form. Scalene four-sided pyramid*. 



Vol. I. Fig. 9. 

 Simple forms. P oo ; P + oo = 90 (nearly) ; 



Pr -f oo ; Pr -f- oo. 

 Char, of Comb. Prismatic. 



* According to PHILLIPS and BROOKE, it is an acute iso- 

 sceles pyramid, the edge at its base being = 140. A combination 

 quoted by PHILLIPS is similar to Fig. 92. having the oblique 

 edges between b and I replaced by the faces of a pyramid, the 

 base of which is = 122 50'. H. 



