ORDER II. HEMI-PRISMATIC LEAD-BARYTE. 137 



in veins, particularly in their higher levels, in various 

 rocks, but they are also found in beds. Upon veins they 

 are accompanied by hexahedral Lead-glance, and various 

 species of the genus Lead-bary te, by prismatic Hal-bary te, 

 dodecahedral Garnet-blende, octahedral Fluor-haloide, 

 rhombohedral Quartz, &c. ; sometimes also by different 

 ores of silver, &c. 



4. Finely crystallised and other varieties are found at 

 Zschopau and other places in Saxony, Przibram, and Mies 

 in Bohemia, Freiburg in the Brisgaw, in Hungary, in the 

 Hartz, at Poullaouen and Huelgoet in Brittany, at Lead- 

 hills and "SVanlockhead in Scotland, in Cornwall, and in 

 several counties of the north of England. The finest 

 crystallised varieties of the arseniate of lead occur at 

 Johanngeorgenstadt in Saxony, in silver veins. 



3. HEMI-PRISMATIC LEAD-BARYTE. 



Prismatic Lead-Spar, or lied Lead-Spar. JAM. Syst. 

 Vol. II. p. 3C6. Hemi-prismatic Lead-Spar,- or Red 

 Lead-Spar. Man. p. 87- Chromate of Lead. PHILL. 

 p. 349. Rothbleierz. WERK. Hoffm. H. B. IV. 1. S. 33. 

 Kallochrom. HAUSM. III. S. 10G4. Chromsaures Blei. 

 LEOKH. S. 246. Plomb chromate. HAUV. Traite', 

 T. III. p. 467. Tabl. comp. p. 81. Traite 7 , 2de Ed. 

 T. III. p. 357. 

 SORET. Ann. des Mines. T. III. p. 481. 



Fundamental form. Scalene four-sided pyramid. 

 P = {{^I g}, 109. 37, 105 45'. Inclina- 

 tion of the axis = 12 3(X in the plane of the 

 short diagonal. Vol. I. Fig. 41. AP. 



a : b : c : d = 4-52 : 4-82 : 5-02 : 1. 



Simpleforms. P- 



P + CD (M) = 93 40'; ; (Pr + c*) 



VOL. II. 



