CORUNDUM IN UNITED STATES. 133 
MONTANA. 
To the west of the Appahichiaii Mountains there are but four- 
States in which corundum is authentically known to occur, namely, 
Montana, Colorado, Idaho, and California. It has been reported 
from Nevada, but no definite information or reference to the locality 
can be obtained. The only localities of any connnercial importance 
are those in Montana, and these are the only ones that are described 
here. The California deposits haye been described on pages 42-44, 
those from Idaho on page 116, and those from Colorado on page 49. 
The corundum dei:>osits in Montana are located in the south-central 
part of Gallatin County, on the headwaters of Elk Creek, in a group 
of foothills between the Gallatin Valley and Spanish Creek Basin. 
They are about 23 miles nearl}^ south of Belgrade, Gallatin County, a 
station on the Northern Pacific Railroad. The corundum occurs in 
a seynite, as described on page 48. The crystals of corundum yary 
from a fraction of an inch up to 8 inches in length, and some haye 
been found that weighed 1-J to 2 pounds. This mineral is not dis- 
tributed evenly throughout the syenite rock, but is sometimes con- 
centrated into seams or streaks from a few inches to 34 inches in 
Avidth. Some of the smaller seams are almost pure corundnm, and 
in the larger ones the percentage varies from 10 to 70 per cent. The 
full width of the corundum-bearing syenite is from 8 to 10 feet, and 
it will average from 5 to 10 per cent of corundum. There are three 
companies which are developing corundum properties in this general 
district, of which the largest and at the present time the most impor- 
tant is the Montana Corundum Company. This company is working 
I property that has been developed by means of shafts, tunnels, pits, 
and crosscuts which show the deposit to be very persistent and reg- 
ular for over 1,000 feet. The property has been thoroughly equipped 
with machinery for mining, cleaning, and preparing the corundum 
for market. The cleaned corundum makes a good abrasive; it has 
I been tested by a number of users of this kind of abrasive material, and 
they have reported favorably regarding it. A fire test has been made 
! on this corundum by the author, and it was proved that it could be 
used in the manufacture of a vitrified wheel. 
The Bozeman Corundum Company has been developing a prop- 
erty about 14 miles southwest from Bozeman. The corundum seams 
j vary from a few inches to 3 feet in thickness, and are being exploited 
I by shafts and drifts. Five miles to the west of the property of the 
i Montana Corundum Company is the Anceny corundum deposit, 
: \yhich is now being developed. 
