118 CORUNDUM, ITS OCCURRENCE AND DISTRIBUTION. 
acres of surface, over most of which the rock is exposed. As is seen 
from this map, most of the mines are located near the contact of the 
dunite with the gneiss or schist, and follow contact veins of corun- 
dum. A number of interior veins have been worked within the for- 
mation, but, with the exception of the one marked " Shaft " on the 
map, they have all soon pinched out. 
Most of the mining has been done on the south side of the forma- 
tion, where was encountered what is known as the Big vein. This 
was first mined by means of open cuts and later by tunnels, the last 
one being about 300 feet below the summit of the hill. PI. X is a 
view of the entrance to this tunnel, and shows the peridotite rock on 
the left and the gneiss on the right beyond the cut. For nearly the 
w^hole distance of the southern boundary of the dunite formation a cut 
has been made following the contour of the hill. This cut was some- 
times wholly within the gneiss, at other times wholly within the peri- 
dotite, and again cutting directly on the contact. The tunnels are all 
to the left of the cut, and they have encountered corundum almost 
continuously for a distance of 1,280 feet, reaching nearly to the south- 
east boundary of the formation. PL XI is a view of the upper or 
southeastern end of this cut, showing the peridotite on the left and the 
gneiss and schist on the right. The upper part of this cut is known 
as the Stanfield mine. A tunnel has been run into the hill near the 
contact, at the head of which the vein of corundum is 8 to 10 feet 
wide. No work has been done at this mine for a number of years. 
On the northeast side of this formation is what is known as the Zeb 
Jones mine, where there was exposed (July, 1899) a bench of ore 25 
feet in depth and 2 to 5 feet in width, uncovered for a distance of 
50 feet, which averaged very close to 50 per cent corundum. This 
vein carries what is known as " buckwheat " corundum, which, as its 
name suggests, is made up of small, irregular particles of corundum 
about the size of buckwheat grains. 
Numerous interior veins have been found and worked, but they can 
be mined profitably only when they are worked in conjunction with 
large border veins, for the reason that they are very likely to pinch 
out after being worked for a short time. 
From these various openings, collectively known as the Corundum 
Hill mine, block, crystal, and sand corundum ores have been obtained, 
all of which can be readily cleaned to make a commercial product 
that can be used in the manufacture of any kind of corundum wheel. 
A small quantity of garnet is occasionally found associated with the 
corundum in the vein along the southern contact, but this portion of 
the ore can be readily eliminated by hand cobl)ing at the mine. This 
property is now owned by the International Corundum and Emery 
Company, of New York, N. Y. 
