4O AGRICULTURAL ANALYSIS 



little if any change of hardness from that at the surface. If this 

 softer breccia, therefore, were passed through a suitable crusher, 

 most of the phosphate would be pulverized, while the chert would 

 remain in much larger blocks. If the material thus treated were 

 passed over a screen with a proper mesh, which could be deter- 

 mined only by experiments, it seems altogether probable that a 

 fairly complete separation would be effected. The process sug- 

 gested above would be a simple and cheap one, and, considering 

 the ease with which the rock can be raised, it seems probable that 

 a cheap and merchantable product could be obtained in this man- 

 ner. 



A part of the lamellar variety would require no further treat- 

 ment than hand picking at the bank. The quantity of such rock, 

 however, is probably not large, and the greater part of this variety 

 will have to be separated from the clay through which it is found 

 disseminated. This would probably necessitate, first, screening in 

 the bank, to separate it from the greater part of the clay ; second, 

 washing, to remove the remainder of the clay; and, third, hand- 

 picking, to remove the free chert with which it is associated. 

 None of these processes are expensive, and if careful prospecting 

 shall show this variety to exist in considerable quantities, it can 

 doubtless be prepared for market at slight expense. It is im- 

 portant, however, for the successful development of these deposits 

 that thorough prospecting should precede the erection of a plant 

 for treating the rock. The prospecting should be done in a sys- 

 tematic manner and by a competent engineer. 



STATISTICS AND COMPOSITION 



42. Tennessee Phosphates. Tennessee produced during the 

 year 1903, 460,530 pounds of phosphate rock containing from 

 77 to So per cent, of lime phosphate. It is well known that 

 almost all of the rich phosphates produced in Florida are ex- 

 ported to Europe. 22 Of the rich phosphates produced in Ten- 

 nessee, however, only about one-fourth are sent to Europe. The 

 other three-fourths are consumed in this country. The Tennessee 

 phosphates are not looked upon with very great favor in Europe 

 because of their content of iron and alumina. Five samples of 

 22 Annales de Chitnie analytique, 1906, 1 1 : 256. 



