26 FLORIDA GEOLOGICAL SURVEY SIXTH ANNUAL REPORT. 



DIATOMACEOUS EARTH. 



The only abrasive material produced in Florida is that known 

 as diatonmceous earth, the best known deposits of which lare 

 located near Eustis in Lake County. In addition to the Lake 

 County deposits, however, a number of samples of a similar mate- 

 rial have been received by the Survey from Polk County, and it is 

 evident that it is widespread in its occurrence. The earth is found 

 chiefly in fresh-water lakes, where it is intimately mixed with 

 peat or muck, the material as taken from the bog having the 

 appearance of peat of a grayish color. The method of treatment 

 is to burn out the carbonaceous matter, the siliceous material re- 

 maining as a very fine powder. The diatomaceous earth mined 

 near Eustis appears to consist largely of the spicules of fresh- 

 water sponges, shells of diatoms and particles of amorphous silica. 



Diatomaceous earth is used largely as a polishing powder for 

 which its hardness and fineness render it particularly suitable. 

 It is also used in some scouring soaps, and to some extent in the 

 manufacture of dynamite as an absorbent for nitroglycerine. It 

 is a good non-conductor of heat and hence is valuable for pack- 

 ing steam pipes, and to some extent for fireproof materials in 

 general. 



Diatomaceous earth was produced in Florida during 19 13 to 

 a limited extent by the Standard Diatomite Company of Eustis. 

 There being only the one producer the output is not separately 

 listed, but is included with the total mineral production of the 

 State. 



The following account of diatomaceous earth in the LTnited 

 States is taken from the report on the Production of Abrasive 

 Materials in 191 3, by Frank J. Katz* : 



Diatomaceous earth, called also infusorial earth and kieselguhr, is a light, 

 earthy material, which from some sources is loose and powdery and from 

 others is more or less firmly coherent. It . often resembles chalk or clay in 

 its physical properties, but can be distinguished at once from chalk by the 

 fact that it does not effervesce when treated with acids. It is generally white 

 or gray in color, but may be brown or even black when mixed with much 

 organic matter. Diatomaceous earth is made up of tests of minute aquatic 

 plants composed of a variety of opal, which, chemically, is hydrous silica. 

 Owing to its porosity it has great absorptive powers and high insulating 



*Mineral Resources of the United States, Calendar Year 1913, Pt. 11, p 268. 



