174 VLORIDA GEOLOGICAL SURVEY-15TH ANNUAL REPORT

 In a series of tests made by the United States Bureau of Standards in 1914 a clay from near Thomas City was included. Its qualities indicate that it may be used for a common building-brick. Its physical properties are:'
 Physical Properties of Thomas City Clay (Bureau of Standards Sample No. 2r).
 Plasticity.......................... G ood.
 W ater of plasticity................. 28.9%
 Linear air shrinkage................. 6.0%
 Fire tests:
Temperature. Linear Shr. Porosity. Color.
 Per Cent. Per Cent.
 950*C. 0.22 35.6 Buff.
 1020 34.0 Buff.
 1050 32.2 Buff.
 1080 33.4 Buff.
 1110 1.09 33.8 Buff.
 1140 33.6 Buff.
 1170 33.6 Buff.
 1200 33.7 Buff.
 1230 0.55 32.8 Buff.
 1260 34.4 Buff.
 1290 33.7 Buff.
 1320 0.49 33.5 Buff.

 LAFAYETTE COUNTY
 Lafayette County lies in the northwestern part of the peninsula and is underlaid by the Ocala and Chattahoochee formations. Both of these contain clays to some extent but none that may be considered of commercial importance.
 LAKE COUNTY
 Lake County lies in the central part of the peninsula in the heart of the Lake Region. Its surface formations are essentially all sand-clays in which there is a high percentage of coarse, sharp, angular sand and some gravel with a good, reddish, clay bond. This material is very desirable for sand-clay road material, but is not adapted to other uses.
 Extensive deposits of sedimentary kaolins also occur in Lake County and are discussed in detail in a subsequent chapter. (Chapter IX.)
 Numerous lacustrine deposits also occur in Lake County. These are usually of limited areal extent and relatively thin.
 One of these occurs on the property of B. H. Nuckolls near Unatilla (Sec. 1, Twp. 18 S., R. 26 E.). This is a blue clay with a bright-red motISellards, E. H., Report of Clay Tests for Paving Brick, Florida Geological Survey Press Bulletin No. 7, 1915.