46 



MINERALS IN VEINS. 



important are iron pyrites, oxide of iron, and clay iron- 

 stone. 



Iron pyrites is composed of iron and sulphur in 

 nearly equal proportions; it is brilliant, of a pale 

 brass-yellow colour, and generally crystallized often 

 in cubes. It scratches glass, and gives fire with steel, 

 and is often taken by the ignorant for gold. This 

 variety is apt to suffer decomposition from expo- 

 sure to the air, becoming covered with a white ef- 

 florescence, which is a sulphate of iron or copperas. 

 In several places in the United States the manufac- 

 ture of copperas from this mineral is carried on ; at 

 Strafford, Vermont, in the year 1825, nearly a thou- 

 sand tons of copperas were produced. 



Oxide of iron is iron combined with oxygen, and 

 differs much in appearance, according to the degree 

 of oxidation and intermixture with other substan- 

 ces ; some varieties being red and earthy, others of 

 a dark brown colour, others of a steel gray, with a 

 bright metallic lustre ; the latter is termed specular 

 iron. Iron in the state of the protoxide is highly 

 magnetic, and forms the native loadstone, but in the 

 state of the peroxide it loses its magnetic qualities. 



Clay iron-stone is a very impure carbonate of iron ; 

 it is generally of a light brown colour, and occurs 

 in large nodular masses in connexion with coal- 

 beds, and also forming deposites in sandstones. 



Masses of native iron, which is malleable and flex- 

 ible, and contains a small quantity of nickel, have 

 been found in various parts of the earth ; one of 

 which, discovered in Louisiana, and now in the 

 Mineralogical Cabinet at New-Haven, weighs up- 

 ward of 3000 pounds. A mass is also in the Im- 

 perial Cabinet at Vienna, which was seen by the 

 inhabitants to fall from the air in the shape of a 

 globe of fire. 



Lead. — The colour of this metal is a bluish gray, 

 which soon tarnishes on exposure to the air. Its 

 ores are numerous, but, with the exception of the 



