PHOSPHATE ROCK: UTILIZATION AS FERTILIZER. 7 



cent tricalcium phosphate, with only very small percentages of iron 

 and aluminum oxides. The average cost of mining the western 

 phosphate is from SI. 50 to $2 a ton. 



Because of their great distance from the fertilizer market, the 

 western deposits have been mined to a very small extent, but the 

 tonnage of high-grade rock in this region far surpasses that of any 

 other area yet discovered. 



THE PHOSPHATES OP ARKANSAS. 



The phosphates of Arkansas are not generally considered of great 

 economic importance, for, though small bodies of high-grade rock 

 have been found in several localities, the average phosphate content 

 is far below that of the rock mined in Tennessee and Florida. 



Mining has been conducted to a considerable extent only in the 

 northern part of the State, in Independence County, about 12 miles 

 from Batesville, a town on the Missouri Pacific Railway. Here the 

 phosphate rock is of Silurian age and occurs in two strata, one 

 directly overlying the other. The upper stratum (from 3§ to 6 

 feet thick) is the only one considered worth mining, and averages 

 about 55 per cent tricalcium phosphate, with 5 or 6 per cent of the 

 combined oxides of iron and aluminum. No mining has been done 

 in these fields for over a year, since it has been found more economical 

 to supply the demand for phosphate from the richer deposits of 

 Tennessee. 



The mining of Arkansas phosphate was conducted in a manner 

 similar to the mining of Tennessee blue-rock phosphate, and the 

 cost of extracting it was approximately the same. 



KENTUCKY PHOSPHATE. 



Several small deposits of high-grade phosphate rock have been 

 found in the Ordovician limestone in Woodford, Scott, Fayette, and 

 Jessamine Counties, Ky. 



The phosphate occurs in thin, close-grained plates, brownish gray 

 in color, and resembles closely the brown-rock phosphate of Ten- 

 nessee. In order to prepare a high-grade product, the material must 

 be put through a washing process like that employed in the brown- 

 rock fields. The cleaned product varies in its content of tricalcium 

 phosphate from 60 to 75 per cent. 



A small amount of development work has been done and a small 

 tonnage shipped from Midway, a little town on the Louisville & 

 Nashville Railroad between Frankfort and Lexington, Ky. So far 

 all the rock sold has been finely ground for direct application to the 

 field. 



