A PRELIMINARY PAPER ON THE FLORIDA 
PHOSPHATE DEPOSITS 
E. H. SELLARDS. 
THE HARD ROCK P H O S PH AT E.—DU N N ELLO N 
FORMATION. 
The area of hard rock phosphate at present productive, lies 
in the western part of central peninsular Florida and extends as 
a narrow strip parallel with the gulf coast in a general north and 
south direction from southern Suwannee and Columbia Counties 
to Hernando County, a distance of one hundred miles. Mining- 
lias been carried on continuously in this section since 1888. Sev¬ 
enty-four plants under the ownership of twenty mining com¬ 
panies operated in this section during 1909. These plants were 
distributed as follows: Suwannee County, one; Columbia Coun¬ 
ty, three; Alachua County, twenty-two; Marion County, twelve; 
Citrus County, thirty-four; Hernando County, two. Owing to 
the depressed condition of the phosphate market a number of 
these plants closed either temporarily or permanently early in the 
year while many others closed before the end of the year. At the 
beginning- of 1910, the number of plants in actual operation was 
.thirty-seven. These plants were distributed as follows: Suwannee 
and Columbia Counties, one plant each; Alachua County, four¬ 
teen plants; Marion County, ei^'ht plants; Citrus County, twelve 
plants; Hernando County, one plant. Each phosphate plant opens 
up in the process of mining one to several pits offering exception¬ 
ally "good exposures of the phosphate bearing formation. The 
following notes are based on observations of the exposures made 
at these and at the many other plants that have operated in this 
section during the past several years. 
LITHOLOGIC DESCRIPTION. 
The phosphate-bearing formation as developed in this sec¬ 
tion includes a mixture of materials from various sources and 
of the most diverse character, further complicated by pronounced 
