15

_ Practically all the ore to be seen . . . . “appears to be on one
claim, and occurs in a fine-grained, greenish andesite at or near its contact
with limestone. The ore consists chiefly of magnetite, with hematite in
minor quantities, both more or less impregnated with copper minerals.
- . . . The main mass of mineral is in the form of a small hill of
almost solid iron ore, about 200 feet wide, and from 300 to 400 feet long.
On the top of the hill generally there are no indications of copper (sulphide)
mh but over the south side of the hill the iron ore carries consider-
able copper. . . . An open-cut on the adjoining hill to the west
5 on o 9 (Gls@loses) Or 5, 5 5 5 O@mby i) to 1D tear , , 2

For further remarks on this deposit, See conclusion of the following
description of the ‘Whitehorse copper belt.”

(6) Whitehorse Copper Belt

Source of Information. McConnell, R.

“The Whitehorse Copper Belt, Yukon Territory”’;
Geol. Sury., Canada, 1909, pp. 7-9, 2

GENERAL DESCRIPTION

Bodies of magnetite with varying amounts of hematite and sulphides
occur within a zone or belt 12 miles long in the valley of Lewes river in the
vicinity of Whitehorse. These bodies have been extensively mined for
their copper contents. The oldest rocks in the immediate vicinity are
limestones of Paleozoic or early Mesozoic age. They have been broken
through and largely destroyed by three successive igneous invasions, so that
only fragments remain. The earliest igneous rocks are porphyrites of
various kinds and form sills up to 1,000 feet thick. Later than them are
bodies of granite, diorite, and gabbro, and intermediate varieties. These
rocks occupy a large part of the district and may be outlying masses of
the Coast Range intrusives. Last of all are very numerous dykes. The
remnants of the limestone are bodies which range in size from such as are
a few feet across to irregular masses several miles long and one or more
miles wide. The beds stand at all attitudes.

The limestone in the vicinity of the granitic areas is metamorphosed
for the most part to a coarsely crystalline rock, but at irregular intervals
the affected zone widens and the limestone is charged in a variable degree
with a great variety of minerals. The iron and copper deposits occur
chiefly in these mineralized zones within the limestone masses, but essentially
similar deposits occur also within the granitic rocks at considerable distances
from any visible limestone. The mineralized bodies seldom occur in the
porphyrites. :

Magnetite and hematite are widely distributed and both occur in large
masses. Magnetite is especially abundant and is seldom absent from the
mineralized areas. Lenses of this mineral range in size from a few inches
up to 360 feet in length and are found at intervals along the whole length
of the mineralized belt, mostly in limestone. Hematite is less common, but
was the principal mineral in one very large body. The largest magnetite
body was 360 feet long. All the magnetite masses are sprinkled with
grains and small masses of bornite and chalcopyrite. Other sulphides
occur, as well as garnet, pyroxene, epidote, ete., the silicates being especially
abundant about the borders of the mineralized areas.

1Cairnes, D. D.: Op. cit., p. 55.