192 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
result is a very interesting complex, which is represented as faithfully 
as possible on the map. But in addition to the lodes shown, the rocks 
in this vicinity are traversed b} r innumerable small veins and fissures 
which can not be indicated on so small a scale. Those shown are 
chiefly strong massive veins of white quartz, sometimes including 
considerable country rock, usually carrying a little rhodonite or rho- 
dochrosite, and not showing much evidence of mineral wealth. They 
frequently branch and are linked together by smaller fissures. 
In the saddle between Lake Como and Ross Basin the remarkably 
thorough manner in which the rock between the main fissures has 
been sheeted is beautifully shown. This minor sheeting is generally 
parallel in strike with the larger lodes. At the particular point where 
the structure was best shown, these sheeting planes dip westerly at 
about 60°. As many as 50 of them may frequently be counted within 
a width of a foot. There has been some infiltration of quartz along 
these minute planes of fracture, which causes them to stand out as 
little parallel ribs on weathered surfaces. The appearance in the 
western part of the saddle is as if a series of finely laminated cherty 
sediments had been tilted up at a high angle. The local strike of this 
sheeting is about N. 35° E., but it is sometimes disturbed by latei 
cross fractures. No regularity or rhythm could be detected in the 
spacing of these minor sheeting planes. The country rock is appar- 
ently andesite, but too altered and decomposed for certain identifica- 
tion. It may be rhyolitic. 
Faulting was not detected along any of the fissures about Lak( 
Como. Study of them was, however, necessarily confined to the 
surface. 
Old Lout and Forest mines. — These properties, situated a mile anc 
a quarter due west of Mineral Point, being closely connected, will b( 
described together. The Old Lout was located about 1876. Shortly 
afterwards it sold for $10,000 and became, in the years of its activity 
the most important mine in the gulch. It has produced betweei 
$300,000 and $400,000 worth of rich silver ore, containing bismuth 
According to the Mint reports, about $200,000 of this amount was pro 
duced in 1884, in which year the mine was the largest producer in tin 
county. It employed about 30 men, raising some 5 tons of ore pe 
day. In 1886 it was sold to a London company for $200,000, and ii 
1887 it is credited with a product of $86,654. The new owners ran «* 
tunnel some 1,800 feet in length, from the bottom of the gulch, bu 
never found the rich ore which had rendered the upper workings prof 
itable, and about the year 1890 operations were abandoned. Th< 
tunnel house and the machinery were subsequently destroyed by fire 
The upper workings were exploited by means of a shaft of unknowi 
depth, which in 1890 was no longer safely accessible. The lower tun 
nel, being partly caved and filled with a strongly flowing stream o 
water, can not now be entered. The ore which came from it indicate 
