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Copper and Silver

The most widespread economic minerals of the map-area are those
containing copper. Chaleopyrite is most common; others include bornite,
chaleocite, and native copper. They are most abundant in lavas, tuffs, and
similar rocks of the Takla group, where they generally occupy parts of
sheared zones or narrow crustified quartz veinlets, or have partly replaced
favourable tuff beds. A few samples from these deposits were assayed, but
none contained appreciable gold. One from the Omineca fault zone, and

another from the Motase claims, contained, respectively, 83-20 and 14-98
ounces of silver a ton.

Omineca Fault

A veinlet about half an inch wide was found in sheared voleanie rocks
of the Omineca fault zone 2 miles southeast of longitude 127 degrees. It
contains chalcopyrite, malachite, azurite, unidentified soft grey minerals,
calcite, and a few quartz crystals. A picked sample contained: gold, 0-205
ounce a ton; silver, 83-20 ounces a ton; and copper, 8:31 per cent.

Dewar Peak

A single piece of float, about 5 inches in diameter and comprising
nearly solid bornite, was found on the valley floor about 14 miles south-
east of Dewar Peak. In addition to copper it contained 0-005 ounce gold
and 4-56 ounces of silver a ton.

Menard Creek

A sheared and breeciated zone about 5 feet wide trends northwesterly
across the top of the ridge just west of the source of Menard Creek.
Adjoining this zone on the northeast is a 15-foot rusty band that, with the
brecciated zone, extends well down both sides of the ridge. Adjacent rocks
are greenstones of the Takla group. The sheared zone contains a little
limonite, malachite, chalcopyrite, and crystalline quartz, and a grab sample
from it assayed: gold, 0-13 ounce a ton; silver, 3-59 ounces a ton; and
copper 5:18 per cent.

North of Sustut Lake

Other copper deposits occur 7 miles slightly east of north from the
outlet of Sustut Lake. A small stock of medium-grained porphyritic diorite
or quartz diorite, correlated with the Omineca intrusions, has invaded dark
green, porphyritic, basaltic lavas of the Takla group. Epidote occupies
widely spaced irregular seams and knots in both rocks, and forms
amygdules in the lava. The intrusion holds scattered blebs of bornite
and secondary malachite, generally less than one-quarter inch in diameter,
and somewhat greater concentrations of these minerals in the epidote-rich
seams. One of these seams, a few inches wide, provided a picked sample that
assayed: gold, 0-01 ounce a ton; silver, 0-51 ounce a ton; and copper, 3-98
per cent. A similar sample from an epidote stringer in the adjacent lava
contained: gold, 0-01 ounce a ton; silver, 0-78 ounce a ton; and copper,
7:90 per cent.

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