216 FLORIDA GEOLOGICAL SURVEY-I5TH ANNUAL REPORT 
CHAPTER IX 
sedimentary KAOEIN 
The Florida clay which has attracted the greatest attention, both 
from a commercial and a scientific point of view, is the “sedimentary 
kaolin”, found at a number of localities in the central part of the pen¬ 
insula. This clay is of interest to the ceramist and the clay operator 
because of its wide field of uses and peculiar characteristics, and to the 
geologist because of its unique occurrence, distribution and associa¬ 
tion with other materials. Much has already been written about this 
unusual clay with reference to its nature, origin and geologic age with¬ 
out these problems being definitely solved. Its physical properties and 
uses, however, are fairly well known. 
TERMINOLOGY 
This clay has been variously known as ball-clay, china-clay, kaolin 
and plastic kaolin. It is commonly marketed under the name of plastic 
kaolin, or china-clay. The term china-clay is used broadly to include 
any white-burning clay, regardless of its origin. The term plastic 
kaolin is misleading in that it might include a residual deposit. The 
term kaolin is applied to a residual white-burning clay of high refrac¬ 
toriness and usually of low plasticity and bonding strength. A ball-clay 
is a plastic, sedimentary clay, white-burning, or nearly so, of high re¬ 
fractoriness, and usually good bonding strength. 
None of these terms, therefore, are entirely satisfactory, as in 
chemical and physical properties the Florida clay is intermediate be¬ 
tween a true kaolin and a ball-clay. Its chemical composition is es¬ 
sentially that of washed kaolins from other regions and its alumina 
content ranges from three to seven per cent higher than is the case in 
the typical ball-clays. The Florida clay also has a much higher plas¬ 
ticity, shrinkage and bonding strength than the true kaolin. In occur¬ 
rence, composition and properties it is very similar to the white coastal 
plain clays of Georgia and South Carolina, except that the Florida 
clays must always be washed before being used. 
The term “sedimentary kaolin” seems best suited for the white 
Florida clay, as this term shows the relationship to a true kaolin and 
