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The mineral occurrences consist of narrow veins and disseminated
deposits of pyrite, chalcopyrite, and molybdenite, associated with large
masses of white quartz in medium-grained, dark green hornblende diorite
of the Omineca intrusions. Stripping and natural erosion have uncovered
quartz at intervals over an area 200 feet long and 60 feet wide, but because
of the large quantity of stream gravels that blanket the deposit, it could
not be determined whether the quartz belongs to one large or several
smaller bodies. Within the quartz are lensy veins of pyrite and molybdenite
up to 4 inches wide, the best exposed of which can be traced for about 20
feet. Stringers of chalcopyrite up to 4 inch wide cut both the quartz and
the hornblende diorite, and appear to represent a stage of mineralization
distinct from that of the pyrite-molybdenite veins. The average sulphide
content of the deposit is very low, and assays for precious metals have
not been encouraging.

The stream gravels contain boulders of rusty, porous magnetite, which,
when crushed and panned, show a few ‘colours’ of gold.

MAGNETITE DEPOSITS NEAR ‘PORPHYRY CREEK’:
SHELL GROUP

Reference: Lord, C. §.: McConnell Creek Map-area, Cassiar District, British
Columbia; Geol. Surv., Canada, Mem. 251, p. 60 (1948).

Bands of magnetite similar to those that must have supplied the
boulders in ‘Porphyry Creek’, referred to above, are known from at least
three places within the watershed of Croydon and ‘Porphyry’ Creeks. The
largest exposed band outcrops mainly on the Shell group of mineral claims,
which lies in McConnell Creek map-area just west of the border of Aiken
Lake map-area, about 2 miles from the ‘Porphyry Creek’ workings. The
magnetite band outcrops in Takla group volcanic rocks cut by several
small intrusive bodies on the mountain slopes above Kliyul Creek, and is
spatially distinct from the chalcopyrite-pyrite deposits on the main body
of Shell group claims, which have been described elsewhere (Lord, 1948,
p. 60). The band is 15 to 20 feet thick, and is exposed in two segments,
with a combined length of more than 1,600 feet, separated by a fault gap
of 600 feet. Throughout this band the magnetite content appears to be
almost everywhere greater than 10 per cent, and a few bodies up to 5 feet
thick and 50 feet long are composed almost entirely of granular magnetite.
The magnetite is accompanied by relatively small amounts of pyrite,
pyrrhotite, and chalcopyrite, with some gold, which is reported to have
been found in grains large enough to be seen with the naked eye. Explora-
tion of this deposit by Springer, Sturgeon Gold Mines, Limited, has
indicated that the copper mineralization, and most probably the gold
mineralization, is later than the fault that offset the rocks containing the
magnetite bodies. No magnetite has been found in the fault, and it appears
that the magnetite was deposited earlier than the sulphide minerals.