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CHAPTER VI
ECONOMIC GEOLOGY
PLACER DEPOSITS

Placer gold may be panned from many streams in the map-area, and
in particular from the bars of the larger rivers, but has been found in
workable quantities at only two localities. Jim May Creek, a tributary of
Osilinka River, has been worked intermittently since 1899, but recovery
has never been large. The paystreak lies in gravels 5 to 12 feet above
bedrock, and appears to represent mainly re-sorted glacial debris, although
some gold has been recovered from a buried preglacial channel, now being
exposed at various points by the rapidly down-cutting stream. The gold
is mainly fine and relatively rounded, although a nugget weighing 1-35
ounces was recovered in 1939. Several bars on Ingenika River have been
worked from time to time, but returns have not warranted continuous
operations. The most productive stretch of the river has been that part
between the mouths of Wrede and Pelly Creeks. In addition, small placer
operations have been carried out on Vega and Wrede Creeks.

It may be noteworthy that although the only significant amount of
placer gold recovered to date in the map-area has come from streams
eroding the highly metamorphosed Lower Cambrian and late Proterozoic
rocks, no lode gold deposits of importance have been found in these rocks.
The younger rocks exposed to the west, in which gold-bearing deposits have
been discovered, have, on the other hand, produced no known local placer
deposits within the map-area, except perhaps on Vega Creek, but have
supplied much of the glacial material mantling the stream valleys now
containing placer gold.

LODE DEPOSITS

The lode deposits in the map-area may be broadly classified on the
basis of geological occurrence as follows: (1) deposits in the highly
metamorphosed late Proterozoic and Lower Cambrian rocks, and in the
Cambrian and late Paleozoic (Cache Creek group) limestones; (2) deposits
in, or grouped around and apparently related to, the Omineca intrusions;
and (38) deposits in post-Paleocene faults.

DeEposiITS IN THE PROTEROZOIC AND Lower CaMBRIAN ROCKS, AND IN
THE Late Pauzozoic LIMESTONES

Mineral deposits in the Lower Cambrian and late Proterozoic rocks,
and in the late Paleozoic (Cache Creek group) limestones, are, with the
exception of relatively unimportant pyrometasomatic pyrrhotite deposits
at the contact of a small stock, typically of the silver, silver-lead, and
silver-lead-zinc types.

As noted in Chapter IV, although the Cambrian and Proterozoic rocks
have been subjected to intense metamorphism and local granitization, the
only apparently definitely intrusive body of any size is a granodiorite stock

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