pbatt.] MODES OF OCCURRENCE. 21 
CORUNDUM IN CHLORITE-SCHIST. 
Besides being associated with chlorites in the peridotites just 
described, corundum is found in the long belts of chlorite-schist that 
traverse the country 10 or 12 miles southeast of Webster, Jackson 
County, N. C. These chlorite rocks, which sometimes attain a width 
of several hundred feet, are traceable for miles across the country. 
Almost the only constituent of these rocks is a green scaly chlorite, 
though sometimes there are present small grains of feldspar, and 
occasionally needles of amphibole. The chlorite is in small scales, 
never very coarse, as is sometimes the case in the zones about the 
peridotite, and often these are so minute as to give the rock a very 
compact appearance. 
In one of these belts, on Caney Fork of Tuckasegee River, Jackson 
County, N. C, corundum is disseminated through the chlorite in small 
rounded masses, ranging in thickness from an inch to minute grains, 
and there the chlorite is not so compacl as elsewhere. The corundum 
is usually wrapped with a white coating of mica, which is a secondary 
mineral derived from the corundum. The mica is often in radiating 
scales perpendicular to the outer surface of the corundum, and while 
in some cases it is very thin, in other cases it has replaced nearly all 
of the corundum, leaving bu1 a grain of that mineral in the center. 
CORUNDUM IN AMPHIBOLITE. 
The occurrence of corundum in amphibolite is important, as the 
large deposits of emery corundum at Chester, Mass.. are found in this 
rock. Under the head of amphibolite are included all those rocks 
that- are composed entirely or chiefly of amphibole's. These rocks occur 
rather widely, including, as they do, those of .Massachusetts, Georgia, 
and North Carolina, but with the exception of those that contain the 
emery they have not, up to the present time, been important in the 
production of corundum. 
Associated with the peridotite rocks of Clay County, N". C, and 
the adjoining Towns County, Ga., are dikes of amphibolite, which are, 
for the most part, between the peridotite and the gneiss, although in 
some places they cut directly across the peridotite formation, but close 
to the contact of that rock with the gneiss. These dikes vary in width 
from 25 to over :><><> feet, their average width being from 75 to 100 feet. 
The relation of these amphibolite dikes to the peridotite formation at 
Buck Creek, Clay County, N. C, is shown in fig. 5. 
The groundmass of this amphibolite is a grass-green amphibole, 
containing 17 per cent of alumina, nearly 12 per cent of lime, and 
one-half of 1 per cent of magnesia, which is best classified under the 
edenite variety of aluminous amphiboles. The rich green color of the 
edenite is undoubtedly due to the presence of a small amount of chro- 
mic oxide, the analysis showing the presence of 0.38 per cent of this 
