130 FLORIDA GEOLOGICAL SURVEY-SEVENTH ANNUAL REPORT. 
PHOSPHATE. 
The phosphate deposits constitute one of the very important 
mineral resources of the Ocala area. These beds, which are fully 
described in a preceding report of the State Survey,* reach their 
maximum thickness in the western part of Marion and the eastern 
part of Citrus Counties. The phosphate from this formation is 
known on the market as “hard rock/’ and is of such purity as to per¬ 
mit a guarantee of 77 to 80 per cent tri-calcium phosphate. 
LIME, LIMESTONE AND MARLS. 
Limestone is found in great abundance in this section and is 
utilized for various purposes. The center of the lime manufacture 
industry of Florida is in and near Ocala, the Ocala limestone being 
used for this purpose. Ground limestone for agricultural purposes 
is also produced by these lime plants. This is used to sweeten the 
soils, and by so doing to increase their productivity. The Ocala 
limestone is also extensively used for road purposes, as the soft 
rock, or marl phase of the formation may be applied to roads di¬ 
rect, being then compacted by a roller or by travel. In places the 
limestone is hard and when crushed makes an excellent concrete 
material. Siliceous boulders are also found in this formation, some 
of which, particularly in the phosphate mines where they are thrown 
out in the process of mining, are crushed for concrete, and other 
purposes. 
Analysis of the Ocala limestone, Ocala. Analysis by the State Chemist 
of Florida for the State Geological Survey. 
Calcium oxide, 55.52%, equivalent to calcium carbonate- 99< I 5% 
Iron and aluminum oxides---- - 35 % 
Insoluble matter, sand, clay, etc.-- .30% 
CLAYS. 
Although not yet utilized, fuller’s earth clays are known from 
the vicinity of Fairfield in Marion County. These beds lie in the 
Alum Bluff formation and with little doubt extend into the area 
covered by this report. Fuller’s earth has been found also at Belle- 
view in Marion County. 
*Fifth Annual Report, Fla. Geol. Surv. pp. 23-80, 1913. 
