PRATT.] 
MODES OF OCCURRENCE. 
13 
c. Yellowish verrniculites, varying considerably in thickness, the maximum 
being 6 to 8 inches; in places absent, so that b comes directly in contact with d: 
where present, c often merges into d. 
(I. Green chlorite, varying in thickness much like c, and in places absent. 
6. Chlorite and corundum, sometimes with a little vermiculite. In places this 
mass maybe largely corundum, and it is what is called the •"corundum vein," 
varying in thickness from a few inches to 12 or 15 feet. 
/. Green chlorite: so far as observed always present, and varying in width from 
1 to 12 inches. 
g. Enstatite: in places hard and compact, and in widths of several feet: usually 
merges into h. 
It. Talcose rock, usually fibrous, varying in thickness from a few inches to sev- 
eral feet. 
j. Dunite, more or less altered, friable, and stained with ferric oxide. 
/,. Dunite, apparently unaltered, quite extensive. 
Between h andj a seam of yellowish day (/) is sometimes observed 
which often contains a narrow seam or fragments of chalcedony. 
I 8 i S0 
1 i/ - - J.£.~-;.-..- - * ^ j i! = \\ I I 
*^fi il 
i! 
In 
Hi • 
l|l|?i 
illilii 
!!i|i !l! ! 
B 
h,r,i! 
Hffii 
; i'i! 
Fig. 1.— Ideal cross section of a corundum contact vein at the Corundum Hill mine, North 
Carolina, a, fresh and unaltered gneiss; b, decayed and unaltered gneiss: c, verrniculites; d, 
green chlorite; c, corundum-bearing zone; /, green chlorite; r/, enstatite; /(, talcose rock; 
i, clay; ,/, altered dunite; fc, unaltered dunite. 
From what could be learned by actual observation and inquiry 
among the miners, rand d are sometimes absent, and when this is the, 
case, e, a mixture of chlorite, vermiculite, and corundum, is seem- 
ingly in direct contad with b. The chlorite, however, on the dunite 
side of the section is const ant. The thickness of the several zones 
(a, b, c, etc.) in such sections varies greatly at different places, and 
the distance across the sections may be said to vary at different 
points, even in the same region, from a few feet to 30 or 40 feet. The 
accompanying diagram (fig. 1 ) represents the cross section of a con- 
tact vein observed at the Corundum Hill mine, Cullasagee, Macon 
County, N. C. 
In the diagram a represents gneiss, apparently fresh and unaltered, 
passing into 6, which has somewhat the appearance of the unaltered 
gneiss, but is so decayed that the particles readily separate from 
