Florida Geological Survey - Geologic Topics
Identification: "Phosphate rock" is a general
term applied to natural deposits of minerals valued chiefly
for their phosphorous content. Phosphate rock is often
called phosphorite. However, it is essentially a
carbonate fluorapatite. The fluorapatite formula is Ca10F2(PO4)6.
The phosphate minerals are only discernible by X-ray and the
electron microscope. Phosphate rock is an earthy material
which varies from a hard rock to a granular, loosely
consolidated mass. The color may be brown, gray, bluish
gray, white, or black.
Occurrence: Florida's phosphate deposits are
primarily of the "land pebble" type, which represent marine
reworking of phosphatic limestones, and deposition of hard
pebbles of phosphate in a gravel bed.
Production: The state is the world's leading
producer of phosphate. Hard-rock phosphate deposits are
mined in Citrus and Marion counties and are known to occur
in a general area extending from Suwannee to Hernando
Uses: Phosphate has a great many uses, the
largest of which is in the manufacture of phosphoric acid,
superphosphate, triple supersphosphate, ground rock and
other phosphatic salts for fertilizer.