ORIGIN OF THE HARD ROCK PHOSPHATES OF 
FLORIDA. 
E. H. SELLARDS. 
Two kinds of phosphate rock are now being mined in Florida,, 
the land pebble and the hard rock. The deposits which carry the 
hard rock phosphate are found over a considerable extent of 
country in the western part of central peninsular Florida. The 
area includes the southern part of Columbia and Suwannee 
Counties, the western part of Alachua and Marion Counties, the 
eastern part of Levy, Citrus and Hernando Counties, and the 
northern part of Pasco County. From north to south the hard 
rock area extends through a distance of about 100 miles. Its 
width from east to west is variable. The greatest width is found 
in Marion County, almost the whole of the western half of this, 
county being included in this belt. West of the Suwannee River 
a limited amount of hard rock phosphate has been fopnd in, 
Lafayette, Taylor and Jefferson Counties. The accompanying 
map shows approximately the extent of the phosphate-bearing 
deposits. The workable deposits are less extensive than*the area, 
here outlined, the mines now operated being confined to a com¬ 
paratively narrow belt reaching from Alachua to Hernando- 
Counties. 
Mining has been carried on continuously in this section for 
more than two decades. Seventy-four plants, under the owner¬ 
ship of twenty mining companies, operated here in 1909, while- 
forty plants, under the ownership of fourteen mining companies,, 
were operating at the close of 1912. Each phosphate plant opens, 
up in the process of mining one to several pits offering excep¬ 
tionally good exposures of the phosphate-bearing formation. The 
following paper is based on observations made in the many pits 
that have been opened up in this section during the past several 
years. The results that are presented in this paper have been 
gradually obtained, and have been published in part in the reports. 
