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 
