6 BULLETIN 312, U. S. DEPARTMENT OF AGRICULTURE. 
thickness of about 1 foot and are mined by means of grab buckets or 
clam-shell dippers. 
The rock as a whole consists of gray nodules of medium hardness, 
frequently much pitted and the holes filled with clay or calcareous 
mud, which must be removed by a washing process. 
The average grade of the marketed product is about 61 per cent 
tricalcium phosphate. The average cost of producing South Caro- 
lina phosphate is not far from $3.46 per ton, including interest, 
overhead, etc., and the rock, on board cars at the mines, brings about 
$4 per ton. 
Since the discovery of the higher grade and more cheaply mined 
phosphates in Florida and Tennessee, the exploitation of South 
Carolina rock has gradually fallen off. Most of the rock now mined 
is consumed locally for the manufacture of acid phosphate and 
double acid phosphate. The latter product, being very rich in 
soluble phosphates, will stand the cost of transportation. 
THE WESTERN PHOSPHATES. 
The western phosphate fields are located in southeastern Idaho, 
western Wyoming, northern Utah, and western Montana. The 
regions in which the phosphate has been mined or developed so far he 
in southeastern Idaho, near the little towns of Soda Springs, George- 
town, and Montpelier on the Oregon Short Line Railroad; along the 
western front of the Sublette Mountain Range, near Border Station 
on the Idaho-Wyoming border; at the south end of this same moun- 
tain range, about 14 miles from Cokeville, Wyo., which is also on the 
Oregon Short Line Railroad; and in the Beckwith Hills in southwest- 
ern Wyoming and in northern Utah along the western front of the 
Crawford Mountains, about 5 miles from Sage Station, Wyo. Practi- 
cally no development work has been done in Montana, but the 
phosphate has been recognized near Melrose, Mont., a town on the 
Oregon Short Line Railroad, and also at Garrison, Philipsburg, and 
Cardwell on the Northern Pacific Railway from 40 to 70 miles north 
of Melrose. 
The topography of much of the phosphate area is extremely rugged, 
but many of the beds of phosphate are readily accessible and within 
easy reach of the railroads mentioned or possible spurs from them. 
The western phosphates are original sedimentary deposits laid down 
when that portion of the earth’s surface was submerged in water. 
The rock is of Carboniferous age and occurs in beds from 2 to 6 feet 
thick, overlain by limestone and phosphatic shales. It ranges in 
color from light gray to jet black and in texture from a readily 
crushed, coarsely oolitic material to a hard massive rock difficult to 
crush. The rock varies in its phosphate content from 65 to 75 per 
