214 FLORIDA GEOLOGICAL SURVEY-I5TH ANNUAL REPORT


 WASHINGTON COUNTY
 Washington County lies in west Florida and is bordered on the west by the Choctawhatchee River. It is underlain by the Chattahoochee, Alum Bluff, Choctawhatchee and Pleistocene formations.
 The only clay of any value found in the county is a flood-plain deposit about two miles southwest of Chipley, which deposit is being worked by the Hall Brick Company for common brick. The nearest railway is two miles and practically all of the product is sold locally.
 The deposit has been proven on about sixty acres and probably underlies a more extensive area. The clay stratum is about three feet in thickness, is overlain by six inches of soil and underlain by sand. The raw clay is black, fairly plastic and has good working qualities. It is cream-burning at the lower temperatures and changes to gray at about cone 1.
 This clay is suitable in its present state for common structural materials such as face and common brick, hollow-block ware, drain tile, etc. It contains a small amount of coarse quartz sand and if this is washed out the clay may be used for stoneware, flower pots, turpentine cups, and similar articles. It has the following physical properties:
 Physical Properties of Hall Brick Company Clay (Lab. No. 0-7).
 Plasticity, judged by feel........... Excellent.
 W ater of plasticity................. 28.80%
 Pore water ........................ 1.13%
 Shrinkage water ................... 27.67%
 Linear air shrinkage................ 9.00%
 Volume air shrinkage............... 27.55%
 Modulus of rupture, average........ 135.4 pounds per square inch.
 Slaking test ....................... 20 hours.
 Steel hard at cone 1.

 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 2.0 21.75 30.80 Cream.
 1050 2.5 20.10 30.50 Cream.
 1150 5.0 11.90 26.40 Gray.
 1190 6.0 9.30 21.50 Gray.
 1230 8.0 6.10 21.02 Gray.
 1310 4.80 13.10 Gray.
 1370 3.84 12.75 Gray.
 1430 12.0 2.59 8.55 Gray.