170 



CLAY 



For a great many years Ohio has led the states in its clay pro- 

 ducts. The fact that a given commonwealth may market more 

 clay products than any other does not imply a corresponding 

 rank in raw clay. In Ohio, however, the supply of clay is very 

 ample. 



The term clay refers to deposits, which are combinations of 

 pure kaolin with one or more of several other minerals, as silicates, 

 oxides, hydrates, and sometimes also certain colloids or organic 

 compounds. When rocks weather, the products are either clay or 

 sand, or both. Silica and claA' are the most common of all rock 

 components. The purer the clay is, theoretically, the higher is its 

 percentage of kaolin. Pure kaolin originates from the decay of 

 feldspar which produces, upon weathering, a hydrous aluminum 

 silicate. Between pure clay and the weathered products which are 



