ORDER II. DI-PRISMATIC LEAD-BARYTE. 133 



It effervesces in dilute nitric acid, and is easily soluble. 

 Before the blowpipe it decrepitates and changes its colour 

 into yellow and red ; if properly managed, it yields a glo- 

 bule of metallic lead. Reduced to powder and thrown 

 upon ignited charcoal, it emits a phosphorescent light. 



3. Among the species of the present geniis the di-pris- 

 matic Lead-baryte is that most commonly found in nature. 

 It occurs in veins and beds in various classes of rocks, ac- 

 companied chiefly by hexahedral Lead-glance, several spe- 

 cies of Baryte and Malachite, Iron-pyrites, dodecahedral 

 Garnet-blende, octahedral Fluor-haloide, and other species. 

 Crystallised varieties are more generally found in higher 

 levels of veins, like other species of the present genus. 



4. Beautiful crystallised and other varieties of the di- 

 prismatic Lead-baryte are found in various mining dis- 

 tricts of Saxony, particularly at Johanngeorgenstadt ; at 

 Clausthal and Zellerfeld in the Hartz ; at Freiburg in 

 Brisgaw; at Tarnowitz in Silesia; at Mies, Przibram, 

 and other places in Bohemia, at Bleiberg in Carinthia, in 

 France, and many other countries of the European conti- 

 nent. Splendid crystals have been brought from the 

 Daurian mountains in Siberia, on the frontiers of China ; 

 fine varieties are found at Wanlockhead and Leadhills in 

 Scotland, in the mines of Cumberland and Durham, at 

 Wheal Crenver in Cornwall, &c. The localities of Black 

 Lead-spar are Freiberg and Zschopau in Saxony, and 

 LeadhiUs in Scotland. Earthy Lead-spar occurs in Poland, 

 Silesia, Siberia, in the district of Eiffel in Germany, &c. 



5. If found in considerable quantities, the present spe- 

 cies is usefully employed as an ore of lead. It is the most 

 important species in this respect after the hexahedral 

 Lead-glance, with which it generally is found and melted 

 together. 



2. RHOMBOHEDRAL LEAD-BARYTE. 



Rhomboidal Lead-Spar. JAM. Syst. Vol. II. p. 369. 

 85. Phosphate of Lead. Arseniate of Lead. 



