232 FLORIDA GEOLOGICAL SUR\EY-I5TH ANNUAL REPORT








 ri r












 Fic. 50.-Empty settling vat. Florida China Clay Company, Okahumpka, Lake County.


 Chemical Analysis of Washed Clay from Edgar. C. Langenbeck, Analyst.l
 Silica (SiO2) ...............................................45.39
 A lum ina (AlO 3) ............................................. 39.19
 Ferric Oxide (Fe2O3) .......................................... 0.45
 L im e (C aO ) .................................................. 0.51
 M agnesia (M gO ) ............................................. 0.29
 A lkalies (N a20, K 20 ) ......................................... 0.83
 W ater (H 20 ) ................................................. 14.01

 T otal ..................................................... 100.67
 MINERALOGY
 Somers2 studied samples of the Florida sedimentary kaolins microscopically and found kaolinite to be abundant, hydromica, fairly abundant; and a few grains of rutile, chlorite, and zircon to be present. He reports that sillimanite was developed in one of the test pieces fired at 1150* C. where the conditions happened to be favorable for its development. He believes it to have been formed from the large flakes of kaolinite or low-grade hydromica.
 USES
 The Florida sedimentary kaolin is used almost exclusively in the white-ware industries. Its principal uses are in making pottery, decorative tile, spark plugs, and electric porcelain.

 1Chemistry of Pottery, p. 100.
 2Somers, R. E., Microscopic Study of Clays included in U. S. Geol. Survey, Bull. 708, p. 292, 1922.