VIEWS SHOWING CHARACTERISTICS OF THE PHOS¬ 
PHATE PEBBLES OF THE BED ROCK MARL AND 
OF THE PHOSPHATE BED. 
Fig. 24.—Phosphate pebbles and cast of a shell washed from the bed rock 
of the Pierce Phosphate Company, Pierce. The shell cast, which is not phos- 
phatized, is from the bed rock in the pit of the Palmetto Phosphate Company, 
Tiger Bay. 
The analysis of these phosphate pebbles is as follows: 
Moisture - .97 
Insoluble matter, sand, etc. - 10.75 
Phosphoric acid, 19.41, equivalent to tricalcium phosphate- 42.39 
Iron and alumina- 0.19 
Calcium oxide, 16.79, equivalent to calcium carbonate- 38.20 
Fig. 25.—Phosphate pebbles and cast of shell washed from the phosphate 
bed in the pit of the Pierce Phosphate Company. The shell cast is phosphatized. 
The following is an analysis of these phosphate pebbles: 
Moisture - 1.81 
Insoluble matter, sand, etc.- 6.62 
Phosphoric acid, 30.67, equivalent to tricalcium phosphate- 66.98 
Iron and alumina- 1.32 
Calcium oxide, 3.05, equivalent to calcium carbonate- 6.94 
The illustrations of phosphate pebbles show that aside from 
chemical composition there is no essential difference between the 
phosphate pebbles of the bed rock marl (Alum Bluff formation) and 
these of the phosphate bed (Bone Valley formation). The pebbles 
are similar in size, shape and structure, except that those from the 
phosphate bed are possibly somewhat more rounded than those from 
the bed rock. The pebbles from the phosphate bed are without ex¬ 
ception higher in calcium phosphate than are those from the bed 
rock, this increase in tri-calcium phosphate being due to secondary 
enrichment as stated in the text, page 69. 
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