ALABAMA MICA DEPOSITS 113 



It contains but little coarse grit but seems to have quite 

 a few small scales of white mica. 



A sieve test shows that all of the clay except 9.7 per 

 cent, passed through a 200 mesh sieve. It would how- 

 ever be desirable to wash the product, or put it through 

 a process of air separation before shipping it to market. 



"A sample of the clay was put through a series of phy- 

 sical tests, but previous to this it was washed through an 

 80 mesh sieve. The porting passing through was then 

 allowed to settle and dried. This washed clay is very 

 white, but its^ plasticity is not very high, in fact it is lean, 

 and has a mealy feel. It would require to be mixed with 

 a more plastic clay before it could be molded in pottery 

 making. 



"With this low plasticity there is also a rather low 

 strength to the material in its air dried condition. This 

 was determined from the modulus of rupture which was 

 40 Ibs. per sq in. 



"The linear shrinkage in air drying was 7 per cent, 

 and is normal. 



"The clay was fired at six different temperatures, and 

 the shrinkage and absorption noted after each except 

 the last. The results follow: 



Temperature Fire Shrinkage Absorption 



950 C. 0.0% Too soft and porous. 



1150C. 4.0% 35.2% 



1190C. 5.0% 3Q.O% 



1230 C. 6.0% 23.5% 



1310C. 6.0% 15.0% 



1730 C. Nearly fused. 



"These tests showed that the clay fires to a very porous 

 body, characteristic of most true kaolins. It does not 

 become steel hard until above 1190 C., and the color after 

 firing is very white. Neither the linear air shrinkage 

 nor the fire shrinkage are excessive. 



"The clay appears to be an excellent one. Its white 

 burning character together with its refractoriness should 

 make it of value in the manufacture of porcelain, white 

 earthenware, electrical insulators, or other wares in 

 which this type of clay is required. 



