88 THE PROSPECTOR'S HANDBOOK. 



PHOSPHATE OP LIME. 



In addition to apatite, phosphates occur in many coun- 

 tries, such as England, France, Russia, in greensand and 

 gault : the nodules frequently contain fossil shells, bones, 

 &c. Also in tertiary formations and in limestone cavities. 



SULPHATE OP BARYTA (Heavy spar). 



Compact, granular, &c., and of a white colour. Slightly 

 harder than rock salt and less than calc spar. S.G-. 4'3 

 4-8. Composed of sulphuric acid and baryta (oxide of 

 barium). Obtained from beds in the Cambro-Silurian foi 

 mations, in carboniferous limestone, &c. When powdered 

 it is used as a paint. 



ASBESTOS. 



Usually fibrous and silky in appearance, from which 

 fireproof articles are manufactured, is a silicate of iron, 

 lime, magnesia, &c. Certain serpentine minerals are fibrous, 

 and have the appearance of asbestos. 



FLUOR-SPAR (see Matrices'). 



Occurs as a matrix in veins through gneiss, clay-slate, 

 also extensively obtained in carboniferous limestone. Used 

 as a flux in the reduction of ores. 



CARBONATE OP LIME (see Matrices). 



Though occasionally as a matrix, carbonate of lime is very 

 plentiful in many countries, and immense formations being 

 common. 



Varieties chalk, oolite, compact limestone, granular 

 limestone (marble), &c. 



Carbonate of lime effervesces in acids and so can be dis- 

 tinguished from a silicate. Used as a flux in the reduction 

 of metallic ores associated with silica, &c. 



