49

They are intruded by a sill of feldspar porphyry exposed in a vertical bluff
about 75 feet high. The intrusive is comprised of about 80 per cent of
prominent white oligoclase phenocrysts. It contains about 1 per cent of
pyrite. Where this sill crosses Porcupine creek about 800 feet to the north-
west it is only 10 feet thick and the sediments overlying it are brown stained
over a width of 50 feet and contain numerous, small, quartz, vein stringers.

Seven Sisters Group (40)
(See Figure 9)

References: Ann. Repts., Minister of Mines, B.C.: 1925, p. 180; 1926, p. 125; 1927,
p. 126; 1928, p. 150; 1929, p. 153; 1930, p. 138.

The Seven Sisters group is on the southwest slope of Seven Sisters
mountain about 8 miles by pack-horse trail from Cedarvale. Sulphide
veins containing silver, lead, and zinc were prospected on these claims by
D. W. Mines, Limited, from 1926 until 1928, and by the Consolidated
Mining and Smelting Company of Canada, Limited, in 1929. There is a
well-built camp at elevation 4,100 feet close to the main workings.

The veins occur in folded sedimentary rocks for 4,000 feet along the
west slope of the mountain between elevations of 4,200 and 4,600 feet. The
sediments include conglomerate, sandstone, greywacke, argillite, and
arkose, with interbedded volcanic tuffs. In the vicinity of the main workings
these rocks strike north and dip 28 degrees east into the mountain, and the
veins are found along faults that have the same strike and dip. Several
hundred feet farther west down the mountain slope the rocks strike north,
but dip 30 degrees west. This indicates that the veins occur at the main
workings on the east limb of an anticlinal fold, the axis of which strikes
north. About 900 feet north of the inclined shaft at Chisholm creek a
number of rock trenches were cut on pyrrhotite veins that occur along
faults of small displacement striking north and dipping 40 to 45 degrees
east. In several of the pits and along the creek the argillites were seen to
strike easterly and to dip 35 degrees north. Here again the veins occur
along the north-plunging nose of the anticline, along faults that
strike parallel to the axis of the anticline. About 1,800 feet north of the
creek, in the vicinity of the Chisholm tunnel, pyrrhotite veins and lenses are
found on the crest of a second anticline, the axis of which also strikes
north. Again the faults and fissures along which the veins were formed lie
roughly parallel to the axis of the fold.

Small dykes of quartz diorite porphyry intrude the sediments and are
older than the veins. A body of diorite is reported some distance north
of the claims.

Where the vein appears strongest, at elevation 4,325 feet, a shaft
inclined at 28 degrees was sunk for about 175 feet and levels were run at
points 50 and 112 feet, respectively, down the shaft. On No. 1 level a
drift run south 110 feet follows much of the way a fault gouge zone 6
inches wide. In several places the gouge gives place to brecciated argillite
up to 2 feet in width containing a little quartz, calcite, and pyrite. The
north drift on this level is 78 feet long with a crosscut east for 23 feet at
a point 28 feet north of the shaft, and a 15-foot crosscut east at the north