. . . . . . . "The Bureau of Mines conducted characterization and beneficiation studies of drill cores of the Hawthorn Formation in northeast Florida. Twenty-three cores from Bradford, Clay, Putnam and St. Johns Counties were processed and analyzed for phosphorus pentoxide content. Studies showed that the core samples were composed of phosphate, quartz, carbonate, and clay; that most of the carbonate and clay was very fine grained; and that concentration of the phosphate by physical means should be possible."@en . . . "The Hawthorn formation of northeastern Florida" . . "The Hawthorn Formation of northeastern Florida"@en . . . . "The Hawthorn formation of northeastern Florida"@en . . . . . . . . . . . . . "Hawthorn Formation." . . . . "From 10 to 25 million years ago" . . "Florida" . .