58

Limited, commenced driving a crosscut adit with the expectation of inter-
secting veins known on other properties north and south of their own
holdings. The adit was started about 250 feet above sea-level and was
made large enough (7 feet by 7 feet) to provide space for drainage and
for haulage of all ore discovered. Work in the adit ceased in 1914 after
a mile of crosscutting and drifting had been done. The adit is known
as the Portland Canal tunnel (See Figure 12). The property was acquired
by the Phoenix Silver Mines, Limited, in 1924, and this company has
since done some development work on surface exposures of veins. The
surface workings were not seen by the writer nor have they been described
in the literature.

The veins crosscut and drifted on by the Portland Canal Tunnels,
Limited, are quartz sulphide veins of varying width, but in general 2 to
6 feet wide. None is of commercial importance where developed in the
adit. The adit, however, proves that the Portland Canal fissure zone has
considerable depth as well as length, and that the veins are little if
at all lower in grade in depth than they are near the surface.

Properties on Portland Canal and Marmot River

SILVERADO MINES, LIMITED

The holdings of the Silverado Mines, Limited, are on the mountain
side southeast of Stewart. The country rocks are breccias and lava flows
of the Bear River formation. The rocks are sheared locally so that in
some places they have been changed into sericite schists.

The early development on the property was done on ore-bearing
veins about 4,000 feet above sea-level. During the past three years,
activity has been centred on veins discovered at an elevation of 1,800
feet. In the autumn of 1927 several new discoveries were made about
4,000 feet above sea-level some distance north of the earliest discoveries.
The property is now controlled by the Premier Gold Mining Company.

The upper workings were not visited by the writer, but have been
described in the annual reports of the Minister of Mines of British
Columbia, from which the following description is compiled. Several
quartz veins mineralized with pyrite and tetrahedrite are exposed in the
workings. Two or three of those on which much of the early work
was done strike northwest and dip gently eastward into the hillside.
They are individually less than 2 feet wide, but contain small shoots
of high-grade silver ore. Two vertical quartz-sulphide veins striking
northwest and each 4 to 6 feet wide occur in the vicinity of the narrow,
ore-bearing veins, but were not developed underground. After several
adits, one of which is at least 400 feet long, had been driven in the
upper veins, development in this part of the group ceased and was
begun on the lower vein showings. The surface showings of the upper
veins are higher grade than the underground showings.

A total of 9 tons of ore was shipped from the upper veins in 1921
and 1925. The ore averaged 150 ounces of silver per ton and contained
3:5 per cent copper.