MINEBK00232

• County: Gilpin
• Volume: 6
• Document: Inspectr
• Suffix: E

_ .T..~-
GEOLOGY.
::; incorpor_

stook The only geologioal eurvey of the diatriot is a partial one
of

Th ~~
contained in the 0eologioal'Exploration of the Fortieth Parallel
e prin-
by Clarence Bing (1870).
ffioe located
Country conk may be generally described as a gneissic, or banded
granite, though having sometimes a distinctly granitic char-
acter. It frequently shows a thinly banded structure
the lines
i. ,
03 banding or bedding dipping easterly. A large intrusion of
quartz porphyry, commonly known as porphy~, is to be seen on the
J
r.
surface dust west of `the shaft, especially in the vicinity of
the`realroad out on'the upper'switoh back. There is reason to
believe that the intrusion has some bearing on the ore deposi-
tion, as the ore shoots occur in clone proximity to the porphyry.
The lodes possess a high degree of parallelism in their strike
wing been
or direction; their course with but few exceptions, being bet-
a lying
keen due east and west on the one hand, and north seat and south
trol of
,crest on the other. The di of the lodes is
p generally at a high
opment
angle, but changes frequ@atly with the depth. The vein shows
little indiaetion of having filled a fissure, as usually under-
atoad, but follows the cleavage points, and in some cases the
follation planes of the gneiss, and replace the country rook
on each side of them. The walla of the veins are usually wsll
defined. The outcrop of the vein may be observed to the west
of the shaft, where the wads has been snored away.
line of
'OOC ft.
ith a small
olty