50

favouring a batholithic source. The writer, therefore, considers the whole
of the Georgia River area of Hazelton group rocks as good prospecting
ground. Some of the veins have been followed for 500 feet or more, but
very little is yet known about the persistence of these veins. Only a
small amount of development work has been done and, therefore, little is
known of the value of the deposits.

DEPOSITS CONSISTING OF CLOSELY SPACED GOLD-QUARTZ VEINLETS

Deposits of this type are known only on the Big Missouri group of
claims in Salmon River district where they occur in tuffs and breccias
that strike north and dip west. Wide zones of these rocks are sparsely
mineralized with disseminated pyrite, galena, chalcopyrite, and sphalerite,
but this material is too low grade to be ore. The mineralized zones follow
closely the strike of the tuffs but it has not been demonstrated that
mineralization follows particular beds. The zones are traversed by veins
of quartz and calcite mostly striking parallel to the strike of the rocks.
In addition veinlets up to a few inches wide, but commonly about an inch
wide and up to 50 feet or so long, are present and appear to be later than
the sulphide mineralization and also later than the quartz and calcite
veins. The veinlets locally contain a high percentage of native gold so
that it would be possible to pick specimens giving phenomenally high
assays. It seems probable that the gold values in the mineralized zones
are carried almost entirely by the veinlets and, therefore, that the number
and richness of the veinlets determine the grade of the mineralized zone.

GOLD-PYRRHOTITE DEPOSITS

Gold-quartz-pyrrhotite deposits occur at Summit lake north of Salmon
river in an intrusive andesite porphyry. The deposits occur both as veins
and as larger, tabular replacements. The veins are of quartz locally well
mineralized with pyrrhotite. The replacements consist of practically solid
pyrrhotite. Both the veins and the replacement deposits contain good
values in gold. Granitic intrusives occur nearby and it is believed that
underlying granites were the source of the deposits.

COPPER DEPOSITS

Copper deposits occur both as veins and as replacements. The deposits
are for the most part in volcanic rocks, but a few are in sediments. The
veins are mostly quartz veins well mineralized locally with chalcopyrite,
pyrite, and arsenopyrite. Gold occurs in most of the veins, but the quantity
is usually less than 0-25 ounce a ton. Jasper is a common gangue mineral
in some veins. The veins are ordinarily 4 to 10 feet wide, but wider and
narrower veins ‘also occur. Many of the veins, especially those in the vol-
canic rocks, can be followed for a thousand feet. The replacements are in
general somewhat leaner than the veins, but locally chalcopyrite may be
plentiful. Gold values also appear to be lower than in the veins. The
replacement deposits may locally be much wider than the veins but do not
attain nearly the same lengths. The replacements in volcanic rocks com-
monly follow certain beds, and in general replacement has not been