RAPPTTTRE TN HXTTED STATES. 107 
river: Emerald Bar, Cheyenne Bar. French Bar, Spokane l^ar. Met- 
ropolitan Bar, Eldorado Bar, Dana Bar, and American Bar. The 
location of these bars is shown on the map (PI. VI). 
A few sapphires have been found as far down the river as Bear- 
tooth, but sapphires have not been found in lar^je quantity below 
American Bar. 
Above Emerald Bar no sapphires have been found on any of 
the bars, but in the gravel of Mag-pie Gulch, less than a mile above 
P^merald Bar (at Canyon Ferry), many have been found by miners 
who were washing the gravel for gold. Xo sapphires have been 
found in place in this gulch, but Kunz " has noted the occurrence of 
some in a dike of vesicular mica-augite-andesite which is about 6 feet 
wide and cuts through the green slate beloAv the gravels. At French 
Bar, about 3 miles below Canyon Ferry, a narrow dike, 3 to 6 feet 
in width, that had greenish sapphires scattered sparingly through it 
was found in 1900. This dike was encountered about 50 feet above 
the river and its strike as it cuts through the slate is X. 10° E., the dip 
being about -1:5° W. This rock is undoubtedh^ of the same character 
as that described by Kunz as occurring at Ruby Bar. 
From the occurrence of these two corundum-bearing dikes of andes- 
ite it would seem that the source of the sapphires found in the various 
bars along the Missouri River is a series of small parallel dikes with 
a slight northeast-southwest trend, like those described. As the 
sapphires are scattered so sparingly through these dikes, the amount 
of decomposition and erosion that was required to liberate those that 
are now found in the gravels must have been enormous. 
The beds of gravel in which the sapphires occur are from 10 to 50 
feet thick and rest for the most part upon slate, in blulfs that rise 
nearly 50 feet above the river. At Emerald Bar the gravel beds are 
nearly 130 feet above the river and rest upon granite rock. 
Most of the mining has been done at Spokane and Eldorado bars. 
The former locality is near the center of the sapphire deposits and on 
the west side of the river about 16 miles due east of Helena. In 1895 
these beds of gravel, which are 8 to 18 feet thick, were extensiA^ely 
mined b}^ an English companj^ known as the Montana Sapphire and 
Ruby Company. The gravels were washed by hydraulic methods and 
a great many gems were obtained, most of which were sent to Eng- 
land. This company also controlled or owned French Bar and Dana 
Bar on the west side of the river and Eldorado Bar on the east side. 
It was reorganized in 1897 as an American company, known as the 
Eldorado Gold and Gem Company, with A. X. Spratt, of Oakland, 
Cal., president, and Frank Spratt, of Helena, Mont., manager. Xo 
« Mineral. Mag., vol. 9, 1891, No. 44, p. 396. 
