94 
MINING GEOLOGY 
northern part of the Sweetgrass arch, or in the minor domes on 
the northern part of the arch, the discovery will prove to be one of 
vast economic importance to Montana. That such is the case 
seems to be indicated by a second success in the Sunburst Oil and 
Gas Company’s well in section 34, township 36 N., range 2 W., on 
June 5. The Sunburst well is producing at a depth of 1,560 feet, 
from a sandstone in the Kootenai formation, about 300 feet strati- 
graphically above the producing sand in the Kevin well. 
Clapp 
Antimony Deposits in Okanogan Valley, Washington. When 
World’s War conditions sent antimony prices soaring from five 
cents a pound to fifty and the Government commandeered all im¬ 
mediate stocks for ammunition purposes, large users of the metal 
had to scour the country for new deposits. Normal purchasers 
scurried hither and thither over the country through all of the 
mining districts wherever the metal had ever been reported. Among 
the occurrences thus revealed were some then recently discovered 
prospects in the Okanogan River valley in north-central Wash¬ 
ington. 
The deposits occur under the shadow of the lofty White Stone 
Peak, about five miles northwest of Tonasket, a station on the 
Oroville Branch of the Great Northern railroad. The country 
rocks are mainly bedded volcanics inclined at an angle of forty 
degrees. Part of the country is a dark colored porphyry, having 
a very fine-grained or almost glassy ground-mass. On the White 
Stone Mountain nearby the bedded volcanics have a thickness of 
upwards of 2,000 feet. 
A number of parallel veins are disposed about twenty-five feet 
apart, and occupy fault-planes. These veins are from a few inches 
to two or three feet in thickness. Wherever the fault-planes are 
intersected by the major bedding planes enlargement of the ore- 
body takes place. Smaller off-shoots penetrate the shattered rock 
in all directions, so that often the country rock assumes the role 
of a low-grade ore-body. The main tunnel happens to be driven 
at right angles to the fault courses, and thus cuts a number of 
veins in succession. A cross-section of the hill on which the chief 
operations are conducted is indicated graphically by the subjoined 
cut (figure 10). 
