A PRELIMINARY REPORT ON CLAYS OF FLORIDA 131


 The Clay County Steam Brick Company's plant located in the north
edge of Green Cove Springs, works a deposit of gray and red mottled, plastic, slightly sandy clay, the presence of which has been proven under about thirty-five acres and probably underlies an even larger area. It
varies from six to ten feet in thickness, has an overburden of loose sand and soil, and overlies a clean, white, sharp sand. The sand underlying the clay is used in cement and concrete construction work in Green Cove Springs. This clay is desirable for common brick and drain tile. A sample taken from the pit face as worked has the following physical properties :

Physical properties of the Clay County Steam Brick Company's Clay (Lab. No. o-43).
 Plasticity, judged by feel............ Excellent.
 W ater of plasticity ................ 25.75%
 Linear air shrinkage................ 10.02%
 Volume air shrinkage............... 31.55%
 Modulus of rupture, average........ 513.2 pounds per square inch.
 Slaking test ....................... 1 hour.
 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 0.2 13.32 30.95 Grayish pink.
 1050 0.2 14.31 31.50 Gray.
 1150 0.2 11.89 28.50 Gray.
 1190 0.3 11.96 28.45 Gray.
 1230 0.8 11.06 22.75 Gray.
 1310 0.8 11.03 20.50 Gray.

 A clay collected by Mr. George T. Lloyd, from SE Sec. 11, T.
7 S., R. 24 E., is suitable for soft, porous, common brick. Its physical properties are:
 Physical Properties of Lloyd Red Burning Clay (Lab. No. o-64).
 Plasticity, judged by feel............ Excellent.
 Water of plasticity ................ 24.20%
 Pore water ........................ 1.07%
 Shrinkage water ................... 23.13%
 Linear air shrinkage................ 10.00%
 Volume air shrinkage............... 30.20%
 Modulus of rupture, average........ .65.4 pounds per square inch.
 Slaking test ....................... 1 hour.
 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950'C. 0.0 14.01 33.00 Light brick red.
 1050 0.5 15.03. 32.50 Light brick red.
 1150 1.0 11.72 28.75 Light brick red.
 1190 1.0 11.21 28.20 Brown.
 1230 1.5 10.60 25.10 Gray.
 1310 2.5 10.50 29.50 Gray.