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Florida Geological Survey - Geologic Topics
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Hardrock Phosphate

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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.
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 counties, north-south.
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.

Hardrock Phosphate

Last updated: July 01, 2015

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