104 ECONOMIC GEOLOGY OF SILVEETON QUADRANGLE. Lbull.182. 
breaks," to signify the character of the rock along the line of which the ore chim- 
neys occurred or might be expected to occur. They were not fissure veins, in that 
the ore bodies did not confine themselves to any given plane, and in following 
them no definite course either laterally or vertically could be counted upon ahead 
of exploration. The course of an ore break I have frequently found to change 90° 
in a depth of several hundred feet. 1 
DISTRIBUTION. 
The stocks do not occur in all portions of the quadrangle, but are 
limited to a small, well-defined area, which corresponds mainly to the 
crest and westerly slope of what may be termed for convenience the 
Red Mountain Range. This district is bounded on the northeast by 
Grey Copper Creek, on the northwest by Red Creek, on the west and 
south by Mineral Creek, and on the east, with one or two exceptions 
near Red Mountain, b} T the ridge crest extending from Anvil Moun- 
tain northward to Red Mountain and thence northeast to the saddle at 
the head of Grey Copper Gulch. The area thus outlined has certain 
characteristic features, apparent to the most unobservant eye. There 
is scarcely an exposure of rock within it which has not been bleached, 
silicified, or otherwise altered, and the whole has been more or less 
thickly impregnated with fine crystals of pyrite. The iron originally 
contained in this pyrite, through weathering and oxidation, has given 
to the Red Mountain Range the beautiful coloring for which the region 
is noted, blending from the deepest red, through vermilion and orange 
tints, to the most delicate yellows ami grays. 
The greater part of the deposits, and all of the more important ones, 
are closely grouped in the northwestern part of this area, in a belt less 
than a mile wide and about 4 miles long, extending from Ironton to a 
point about a mile south of Red Mountain village. 
Although no continuous fissures or veins can be detected on the 
surface, it is noteworthy that the St. Paul, Congress, Senate, Hudson, 
Enterprise, Charter Oak, Genesee- Vanderbilt, Yankee Girl, Robin- 
son, Guston, White Cloud, and Silver Bell mines all lie close to a 
straight line bearing about N. 21° E. The National Belle, Paymas- 
ter, and Grand Prize mines, and a host of less-noted claims, are 
apparently irregularly disposed on either side of this line. (Fig. 10.) 
South of the vicinity 7 of Red Mountain the stock deposits are scat- 
tered and have not proved of much importance. The only one which 
has produced ore in important amounts is that of the Zuni mine, on 
Anvil Mountain, which, however, is interesting chiefly as the source 
of the minerals guitermanite and zunyite. 
ORIGIN OF THE SPACES NOW FILLED WITH ORE. 
In seeking the origin of the ore spaces, there are, in spite of the 
present obstacles in the way of complete investigation, certain facts 
'Trans. Am. Inst. Min. Eng., Vol. XXVI, 1896, p. 1057 
