124 FLORIDA GEOLOGICAL SURVEY—I5TH ANNUAL REPORT 
A brown sandy clay occurs in numerous places in the region just 
west of Gainesville. Here the clay at times immediately overlies the 
Ocala limestone and at other times is underlain by a sand. It can only 
be used for a low-grade, soft, porous common brick. A common-brick 
plant was formerly operated about two miles northwest of Gainesville. 
A sample from the property of D. J. Richbourg, four miles southwest of 
Gainesville, has the following physical properties: 
Physical Properties of D. J. Richbourg Clay (Lab. No. 0 - 45 ). 
Plasticity, judged by feel. 
Water of plasticity . 
Linear air shrinkage.*. 
Volume air shrinkage. 
Modulus of rupture, average. 
Slaking test . 
Fire tests: 
Temperature. Linear Shr. Absorption. 
Per Cent. 
Per Cent. 
950°C. 
1.0 
15.07 
1050 
1.5 
16.44 
1150 
1.5 
15.77 
1190 
2.2 
15.67 
Fair. 
23.90% 
4.5 % 
22.55% 
255.4 pounds per square inch. 
5 minutes. 
Porosity. Color. 
Per Cent. 
36.10 
Brick red. 
34.10 
Brown. 
33.90 
Brown. 
32.40 
Chocolate brown. 
Some residual clays from the Ocala limestone occur in the southwest 
portion of the county. These warp and crack badly and hence are prac¬ 
tically unusable. 
BAKER COUNTY 
Baker County Is located in the northeast part of the State. The 
surface materials consist of yellow and brownish sandy clays and sands, 
with the Alum Bluff formation underlying much of this loose material. 
The clays are of little value from a commercial standpoint. A clay which 
occurs about a half-mile southeast of Macclenny on the Maxville road 
was formerly used for common brick, but only a soft, porous, sandy 
common brick can be made from it. Its physical properties are: 
Physical Properties of Macclenny Clay (Lab. No. c- 6 i). 
Plasticity, judged by feel. .. . 
Water of plasticity . 
Pore water . 
Shrinkage water. 
Linear air shrinkage. 
Volume air shrinkage. 
Modulus of rupture, average 
Slaking test... 
Excellent. 
21.40% 
0.38% 
21 . 02 % 
7.1 % 
15.6% 
105.2 pounds per square inch. 
1 hour. 
