CORUNDUM IN IGNEOUS ROCKS. 
37 
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do, however, make handsome mineral specimens. In fig. 10 there is 
ilhistrated a mass of corundum in amphibolite from Buck Creek. 
Near Elf, Clay County, N. C, a similar occurrence of corundum in 
amphibolite has been observed Avhere this rock cuts a ty})ical dunite. 
At the Isbel mine, at the head of Shooting Creek, in Chiy County, 
N. C, corundum occurs irregularly, and is sparingly disseminated 
through a decomposed hornblendic rock in small grains and masses. 
The least decayed portions of the rock seem to possess the characters 
of an amphibolite, but this could not be determined with certainty. 
The corundum occurs through the mass of this rock across an outcrop 
about 153 feet wide. In most of it the rhombohedral ])arting is 
distinctly developed. 
Three miles east of Marshall and half a mile northeast of the mouth 
of Ivy River, in Madison 
County, N. C, numerous 
crystals of corundum 
have been found over the 
surface of a large out- 
crop of coarsely crystal- 
lized dark-green amphibo- 
lite. In places the rock 
is of finer texture and 
contains some feldspar 
and biotite, passing into 
a dioritic facies. The 
country rock inclosing 
the amphibolite is a bio- 
tite-gneiss. Most of the 
corundum is in large, rough, hexagonal prisms. A crystal with three 
smaller prisms in twin position on alternate hexagonal edges Avas 
found which weighed IT pounds. 
Doubtless many of the occurrences of corundum with chlorite- 
schist (described herein) would be found, if explored to some depth, 
to belong with the amphibolites, as at the Track Rock mine, in Union 
County, Ga., where extensive outcrops of chlorite-schist have been 
found to consist chiefly of bright-green hornblende in the tunnel 
driven into the mountain side. Some portions of it also carry small 
quantities of olivine, possibly passing into amphibole-peridotite. 
On the eastern slope of the Blue Ridge, in the vicinity of States- 
ville, Iredell County, N. C, corundum has been found associated 
wdth an amphibolite composed of a dark-green hornblende. On 
account of the thickness of the soil and the depth to which these 
rocks have been decomposed, there are few places where the fi'esh 
rocks are exposed, and little is known of their extent. At Hunters, 
/'./ 
Fig. 10. 
Mass of corundum in amphibolite from Buck 
Creek, Nortli Carolina. 
