ANTIMONY. 



thus distinguishing it from magnesia in a mineral (see 

 p. 29). 



The principal ores besides corundum (H. 9), found in 

 great quantity in crystalline rocks in America, and from 

 which aluminium is extracted, are 



Boauxite. 



Of various colours. Sometimes made up of concretionary 

 grains. Also as clay (sometimes coloured by iron oxide). 



S.G. 2-55. 



Contains sometimes more than 50 per cent, of alumina 

 (or more than one-third aluminium), the rest being sesqui- 

 oxide of iron, silica (in small quantity), and water. Is 

 soluble in sulphuric acid. 



Cryolite. 



A semi-transparent, brittle mineral. 



Colour whitish yellow, reddish, or black. 



H. 2-5 ; S.GL 3. 



Is a double fluoride of aluminium and sodium, and con- 

 tains sometimes 13 per cent, of aluminium. Easily fusible 

 in candle flame. 



Beauxite is chiefly found near Aries, in the south of 

 France. A rather similar clay has been found in Ireland. 



Cryolite is obtained in Greenland (in gneiss), also in 

 America. 



Aluminium is of a white colour, easily polished, adapted 

 for casting into moulds, does not become tarnished on ex- 

 posure to the atmosphere, and hence is suitable for very 

 many purposes. 



ANTIMONY. 



The metal is usually found combined with sulphur, 

 arsenic, or sulphur and lead. If a mineral be supposed to 

 contain antimony in any form, the presence of the metal 

 may be known by treating the specimen with carbonate of 

 soda on charcoal in the R.F.* of the blowpipe, when, if it 



* (N.B. O.F, Oxidizing Flame; R.F.-=i Reducing Flame ; B.F. = 

 Blowpipe Flame; S. G. = Specific Gravity ; H. = Hardness. \ 



