ORES OF LEAD. 15J 



Composition. Pb 0* Cr= Chromium trioxide 31*1, lead 

 oxide 08 -9. Blackens and fuses, and forms a shining slag 

 containing globules of lead. 



Obs. Occurs in gneiss at Beresof in Siberia, and also in 

 Brazil. This is the chrome yeMoiv of the painters. 



Phcenicochroite (or Melanochroite) is another lead chromate, contain- 

 in o- 23*0 of chromium trioxide, and having a dark red color ; streak 

 brick-red. Crystals usually tabular and reticulately arranged. G. =5 *75. 

 From Siberia. 



Vauquelinite. A lead and copper chromate, of a very dark green 

 or pearly black color, occurring usually in minute irregularly aggre- 

 gated crystals ; also reniform and massive. H. =2*5-3. G. =5*5-5*8. 

 From Siberia and Brazil ; also at the lead mine near Sing Sing, in 

 mammillary concretions. 



Stolzite, or lead tungstate. In square octahedrons or prisms. Color 

 green, gray, brown, or red. Lustre resinous. H. =2*5-3. G. =7*9- 

 8 1. Contains 51 of tungstic acid and 49 of lead. 



Wulfenite, or lead molybdate. In dull-yellow octahedral crystals, 

 and also massive. Lustre resinous. Contains molybdenum trioxide 

 34*25, protoxide 64*42. From Bleiberg and elsewhere in Carinthia ; 

 also Hungary. It has been found in small quantities in the Southamp- 

 ton lead mine, Mass., and in fine crystals, at Phcenixville, Penn. 



Lead SulpJialo-carbonates. There are two whitish or grayish ores 

 of this composition called Lanarkite and Lcadhillite. The former con- 

 tains 71 per cent, of carbonate of lead ; the latter, 47. 



Pyromorphite. — Lead Phosphate. 



Hexagonal. In hexagonal prisms ; often 

 in crusts made of crystals. Also in globules 

 or reniform, with a radiated structure. 



Color bright green to brown ; sometimes 

 fine orange-yellow, owing to an intermix- 

 ture with chromate of lead. Streak white 

 or nearly so. Lustre more or less resinous. 

 Nearly transparent to subtranslucent. Brit- 

 tle. H. =3-5-4. G. = 6*5-7-1. 



Composition. Pb 3 O s P 2 + 1 Pb Cl 2 = Phos- 

 phorus pentoxide 15*71, lead oxide 82-27, chlorine 2*62 

 = 100-60. B.B. fuses easily in the forceps, coloring the 

 flame bluish green. On charcoal fuses, and on cooling, 

 the globule becomes angular ; the coal is coated white from 

 the chloride, and nearer the assay, yellow from lead oxide. 

 Soluble in nitric acid. 



Diff. Has some resemblance to beryl and apatite ; but is 

 quite different in its action before the blowpipe, and much 

 higher in specific gravity. 



