MINERALOGY. 461 



When abundant, this ore is wrought for lead. Large 

 quantities occur about the mines of the Mississippi val- 

 ley. Carbonate of lead is the White Lead of com- 

 merce, so extensively used as a paint. The material for 

 this purpose is, however, artificially made, being pre- 

 pared from sheet lead by the process with vinegar and 

 wine lees. Carbonate of lead, mixed with sulphur and 

 barytes, forms what is called Venice White. Caledo- 

 nite is a compound of the carbonates of lead, copper, 

 and sulphate of lead. In crystals ; from lead hills and 

 red gill ; also from the Missouri mines. 



Malachite Green Carbonate of Copper. Usually in 

 incrustations, partly earth-like, partly tuberous ; struc- 

 ture firmly fibrous. Color light green, sometimes very 

 bright. Crystals transparent, luster adamantine, nearly 

 opaque; heated in a matrass, yields water, and black- 

 ens ; fuses on charcoal, and affords a globule of copper ; 

 dissolves with effervescence in acids. H. = 3.5 to 4.0. 

 G. = 3.6 to 4.0. Green malachite usually accompanies 

 other copper ores ; found in all the mines of the north 

 in both hemispheres, those of Siberia, the Ural moun- 

 tains, the Hartz in Hungary, are the most noted foreign 

 localities. Connecticut, New Jersey, Maryland, Penn- 

 sylvania and Wisconsin have afforded handsome speci- 

 mens; the ore from the Peccatonica, Wisconsin, has 

 been smelted on the spot and exported to England. This 

 mineral receives a high polish, and on this account, a,s 

 well as that of its beautiful color, is sometimes set and 

 used as jewelry ; in Russia, where it is obtained in very 

 large masses, it is made into vases, slabs for tables, man- 

 tle-pieces, etc., which are of exquisite beauty, owing to 

 the delicate shadings of the radiations and zones of color. 



