292 
FLORIDA STATE GEOLOGICAL SURVEY. 
sible ,to introduce day and night shifts in the Withlacoochee River 
mines, one or two plants near Dunnellon having been so operated 
during 1912. The total number of plants mining hard rock phos¬ 
phate at the beginning of 1912 was forty-three. Some of these 
worked out deposits or for other reasons closed down, while 
several new plants opened up. Forty plants were operating in 
the hard rock section at the close of the year. 
The domestic shipments of hard rock phosphate during 1912 
ampunted to 15,425 tons, of which 10,449 tons were consigned 
for use in Florida. The amount of hard rock consigned for 
export, as reported by the producers, was 473,639 tons, as against 
462,072 tons during 1911. The amount of hard rock phosphate 
actually loaded for shipment during 1912 at the various ports was 
470,354 tons. 
PEBBLE phosphate. 
The production of pebble phosphate during 1912 shows a 
slight increase over that of 1911. The output of pebble for 1911 
was 2,020,478 tons, while during 1912 the output was 2,043,486 
tons. The number of plants engaged in mining pebble phosphate 
in Florida during 1912 was sixteen, although several mines are 
frequently worked from one plant. The overburden from the 
pebble rock is removed by steam shovel or by hydraulics. The 
rock itself is mined by hydraulics or by steam shovel. Many of 
the pebble mines run day and night shifts. 
The amount of pebble phosphate consigned during 1912 for 
domestic use, as reported by the producers, was 1,204,502 tons, of 
which 32,425 tons were consigned for use in Florida. The amount 
of pebble rock consigned for export during 1912, as reported by 
the producers, was 682,232 tons. The amount of phosphate 
actually loaded and cleared for shipments through the several 
ports during the calendar year 1912, as reported in the American 
Fertilizer, January 25, 1913, was 732,651 tons, from which it 
appears probable that a -small amount of phosphate sold by the 
producers to parties in the United States and hence reported by 
them as domestic shipments, was subsequently exported. The 
amount of phosphate actually loaded at the ports is used in giving 
