OcroBER 11, 1918] 
ical industries, and in the manufacture of 
electric batteries. There are four commercial 
sources of manganese—manganese ores, man- 
ganiferous iron ores, manganiferous silver ores 
and manganiferous residuum from roasting 
zine from an ore containing zine, iron and 
manganese minerals. Under normal condi- 
tions the world’s supply of manganese ore has 
come mainly from India, Brazil and Russia, 
but owing to the derangement of ocean trans- 
portation and of the foreign manganese indus- 
try only the deposits of Brazil are now avail- 
able to the United States, and these can not 
be drawn upon freely because of the scarcity 
of ships and the long shipment. 
The deposits of manganese ore in the Car- 
tersville district, Ga., have recently been ex- 
amined by Laurence LaForge, geologist of 
the United States Geological Survey, Depart- 
ment of the Interior, in cooperation with Mr. 
J. P. D. Hull, assistant state geologist of 
Georgia, and Professor W. R. Crane, of the 
United States Bureau of Mines. The ore de- 
posits occur in a belt, 1 to 3 miles wide and 18 
miles long, on the east side of the Coosa Val- 
ley, at the base of and on the western slopes of 
the hills that form the western margin of the 
Piedmont Plateau. This belt is in the eastern 
part of Bartow county, and the city of Car- 
tersville is on its west side near its south end 
A branch of the Lonisville & Nashville Rail- 
road extends along the west side of the belt 
and spur tracks reach several uf the larger 
mines. Iron ore, ocher and barite are also 
mined in this belt, and some of the mines pro- 
duce two or more of these minerals. 
The result of the examination is encourag- 
ing, for, although the district is an old one, 
the field studies of the geologists and the ex- 
ploratory work of the mining companies have 
revealed the existence in it of large reserves 
of both high-grade manganese ore and manga- 
niferous iron ore. In recent years little man- 
ganese ore has been mined in this district, but 
the necessity of the war and the curtailment of 
imports which have stimulated the produc- 
tion of domestic ore have caused a revrval of 
mining there. 
The workable manganese ores occur in part 
SCIENCE 
361 
in vein and replacement deposits and in part 
in detrital deposits. The ores in the vein and 
replacement deposits are believed to have been 
deposited from surface water that carried in 
solution material leached from a considerable 
thickness of weathered rock, or, in places, 
from other older deposits of the same sort. 
The detrital deposits are scattered through a 
widespread thick surficial mantle of rock waste, 
wash and alluvium. The deposits of poth 
types are extremely irregular in character and 
occurrence. They include both hard and soft 
ore and both pyrolusite and psilomelane, and 
perhaps manganite, though pyrolusite seems to 
be more abundant. Both types include large 
bodies of manganiferous limonite. 
The vein and replacement deposits are 
found mainly in residual clay and fragments 
of rock derived by weathering from a siliceous 
limestone, or in a breccia made up chiefly of 
the shattered, weathered and somewhat dis- 
placed upper beds of quartzite that lies beneath 
the limestone. Some, however, are found at or 
near the base of the thick surficial blanket of 
rock waste and alluvium, in which detrital 
ores also occur. The manganese minerals 
occur as coatings on or as veins filling crevices 
in the quartzite; as irregular veins, sheets and 
pockets in both residual clay and alluvial ma- 
terial; and as stalactitic or mammillary con- 
cretions in the clay. 
The hard rock that underlies most of the 
vein and replacement deposits is the Weisner 
quartzite, which was once overlain by the lime- 
stone that has been called the Beaver lime- 
stone, both Lower Cambrian formations. Beds 
of siliceous dolomite still remain, but nearly 
everywhere the soluble material of the lime- 
stone has been removed and nothing is left to 
indicate its former presence but a dense lumpy 
dark-red clay or masses of chert fragments in 
a red clay matrix. The strata have been 
sharply folded and have been displaced by 
many small thrust faults, so that the resulting 
structure is very complex. 
The high-grade ore of the Cartersville dis- 
trict, as shown by the average of analyses of 
about 1,600 tons of material shipped within 
the last few months, contains about 42 per 
