The Phosphates of America. 



77 



3. Soft white phosphate, in which no bowlders are found. 



4. Pebble phosphate from Peace River as sent to market. 



5. Pebble phosphate from Polk County drift beds, washed and 

 screened. 



In working or quarrying the "hard-rock" or "high-grade 

 bowlder" deposits, the details of most importance are the careful 

 selection by conscientious and capable superintendents of the dif- 

 ferent qualities, and the accurate sampling and analyses of the 

 different piles before shipment. There is at present a less remuner- 

 ative market in this country than in Europe for the richest grades, 

 and it is therefore probable that for some time to come the entire 

 production of hard rock will be exported. As we have already 

 said and shall more fully explain later on, the majority of foreign 

 manufacturers will make no contracts for a raw material which 

 contains a higher maximum than three per cent, of oxides of iron 

 and alumina. To make shipments within this limit must conse- 

 quently be the aim of the miners who would establish a good rep- 

 utation, and nothing but experience in actual work, harmoniously 

 conducted between the mine and the laboratory, can be relied upon 

 in the great majority of cases to accomplish it. To ourselves this 

 matter has been a source of constant preoccupation, and in the 

 mines with which we are professionally connected we have now 

 succeeded in reducing objectionable constituents to a minimum by 

 adopting the following general scheme of work : 



The pockets are located by boring and by confirmatory pits, and 

 the results of these operations are daily transferred to a map. The 

 pits are carefully sampled, foot by foot, as they go down, and the 

 various qualities of "bowlder," '-'soft white," "gravel," etc., are 

 sent to the laboratory with ample details of their origin. The re- 

 sults of the analyses are daily placed upon the map, side by side 

 with the other details of the survey. 



We thus finally acquire a geological and chemical map of our 



