METALS AND THEIR ORES. 43 



tons. As you will see in another part of this book, the 

 geologist has found clear proof that the native copper of 

 this region was produced in Nature's great furnaces from 

 ores of the metal ages upon ages before the creation of 

 man. 



The sulphurets of copper and the sulphate were no- 

 ticed in the preceding chapter. I go on now to notice 

 the principal of the other ores of this metal. 



78. Oxyds of Copper. There are two oxyds, a red and 

 a black one. The metal can be obtained from them by 

 heating with charcoal, the oxygen uniting with the car- 

 bon to form carbonic acid gas, which flies off. 



79. Carbonates of Copper. There are two carbonates. 

 One of them, called malachite, is of a light green color, 

 and, as it is capable of a high polish, it is used in various 

 ways for ornamental articles. Its value, when manufac- 

 tured as veneering or inlaid work, is about three guineas 

 per pound, and there are at least two pounds and a half 

 in a square foot of finished work. In Russia, where large 

 pieces of it can be obtained, slabs for tables, mantle- 

 pieces, vases, etc., are made from it. The blue carbonate 

 sometimes presents splendid crystals. 



80. Silicate of Copper. This mineral, a compound of 

 silica or silicic acid with oxyd of copper, has a bluish-' 

 green color. Sometimes the green carbonate and this 

 silicate are united in one mineral. 



81. Lead. Native lead is exceedingly rare. Its most 

 common ore, galena, and the sulphate I noticed in the 

 preceding chapter. The oxyd of lead, minium, is what 

 is commonly called red lead. The carbonate is the white 

 lead of commerce. The chr ornate of lead is the chrome 

 yellow used by painters. 



82. Tin. The native metal is exceedingly rare. The 

 chief ore is an oxyd, the sulphuret being seldom found. 

 This is an ingredient in pewter and bronze, and in the 

 amalgam put on the backs of mirrors, and some of its 

 salts are employed in dyeing. The tin used in making 



