44" SCIENTIFIC RECREATIONS 



furnishes us with most of our copper. There is also the "grey" copper ore, 

 which contains various metals ; even silver is obtained from it at times. 



BISMUTH gives us only a few minerals, of secondary importance. 

 Native bismuth resembles antimony, but is reddish in hue. Bismuth ochre, 

 bismuth blende, and bismuthine are the chief combinations. 



LEAD is more important, and is obtained from galena, the sulphide of 

 lead, which is very abundant, and the principal lead ore. It can be at once 

 distinguished by its high specific gravity and metallic lustre ; the " cubic 

 cleavage" also is very easy. It frequently is found containing silver, and 

 even gold, antimony, iron, etc. There are several suphantimonites of lead, 

 such as zinkenite, geocronite, etc., and the salts, such as sulphate of lead and 

 white lead ore, or carbonate of lead (cerasite). The chromate of lead is 

 found in the Ural Mountains. 



TIN is not found in a native state, but as tinstone, or binoxide of tin, 

 named cassiterite. It is found largely in Cornwall, and the mines there have 

 yielded great quantities for generations. Tin pyrites, a union of sulphides 

 of tin, iron,' and copper, is also found in Cornwall. 



ZINC is produced from the ore called (zinc) blende, or sulphide of zinc 

 (black Jack). Its colour is very variable, sometimes red, but when pure is 

 greenish-yellow. It is also found black and brown. The red oxide of zinc 

 (or spartalite) is also worked for zinc. The carbonate, or zinc spar, is 

 common, and used to make brass, as is calamine, which is possessed of a 

 remarkable lustre, and is even luminous when rubbed. It is a silicious 

 oxide of zinc, and is found in the sedimentary rocks. When heated, it 

 displays strong electric properties. 



CHROMIUM occurs in very few mineral combinations ; chromate of lead, 

 chrome iron, and chrome ochre, or sesqui-oxide of chromium are the only 

 important ones. 



ANTIMONY minerals are very hard; the tersulphide is the most common, 

 and from this the metallic antimony is produced. Red antimony, the oxide, 

 is a rarer ore. 



ARSENIC resembles antimony, and occurs in combination with many 

 metals. White arsenic, or arsenious acid, is found in Bohemia, Alsace, 

 Transylvania, etc. Orpiment and realgar are sulphides of arsenic, and are 

 employed as colouring matters in paint and fireworks. Arsenic is very 

 poisonous. 



MERCURY is occasionally found native, but more generally as cinnabar. 

 Chloride of mercury (or calomel) is found associated with the cinnabar, or 



