LEAD ORES. 



281 



angle site. — Sulphate of Lead. 



Primary form a right rhombic prism, with imperfect lat 

 eral cleavage. M : M=103° 38'. Often in slender im 

 planted crystals. Also massive ; lamellar or granular. 



Color white or slightly gray or green. Luster adaman- 

 tine ; sometimes a little resinous or vitreous. Transparent 

 to nearly opaque. Brittle. H=275 — 3. Gr=6'25— 6-3 



Composition : a sulphate of lead, containing about 73 pei 

 cent, of oxyd of lead. Fuses before the blowpipe lo a slag 

 and yields lead with carbonate of soda. 



Dif Resembles somewhat some of the zeolite minerals,- 

 and also arragonite and some other earthy species ; but thh 

 and the other ores of lead are at once distinguished by spe- 

 cific gravity, and also by their yielding lead in blowpipe 

 trials. Differs from the carbonate of lead in not dissolving 

 with effervescence in nitric acid. 



Obs. Usually associated with galena, and results from 

 its decomposition. Occurs in fine crystals at Leadhills and 

 Wanlockhead, Great Britain, and also at other foreign lead 

 mines. In the United States, it is found at the lead mines 

 of Missouri and Wisconsin ; in splendid crystallizations at 

 Phenixville, Pa. ; sparingly at the Walton gold mine, Louisa 

 county, Va. ; at Southampton, Mass. 



Cupreous anglesite. A hydrous azure-blue sulphate of lead and 

 copper. It is remarkable for a very perfect cleavage in one direction, 

 and another inclined to the first 102° 45'. Gr=5 3 — 5-5. From Lead- 

 hills and Roughten Gill, England. Very rare. 



cKhUsiTE. — white lead ore. — Carbonate of Lead. 

 Trimetric. In modified right rhombic prisms. M : M=a 

 1 2 3 



117° 13. M : e=121° 24 ; a : a = 140° 15'. Often ii 



What is the appearance of anglesite ? its composition ? How is it 

 distinguished from arragonite and the zeolites ] What is the crystal" 

 Jization of white lead ere 1 



