35

The largest mineral deposit exposed on the property is tabular and
consists of chalcopyrite and pyrite in a gangue of country rock and
quartz. This deposit strikes northeast and probably dips northwestward.
The apparent width varies from 3 to 15 feet. The length is not proved,
but occasional open-cuts along the line of strike expose similar minerali-
zation which may be continuous for a distance of 500 feet or more. At
one place a sample across 3 feet at the surface of the mineral body assayed
10 per cent copper. The adit was driven under the deposit, but although
it crosscut chalcopyrite-bearing quartz stringers, it did not encounter com-
mercial ore. The deposit may be a replacement along the bedding of the
rocks or it may be a vein in a fracture zone.

Other copper-bearing mineral deposits are present on the property,
but have not been explored sufficiently to trace out their boundaries.

The mineral deposits on this group of claims are large enough to
warrant extensive exploration.

SILVER-LEAD-ZINC DEPOSITS
Deposits on American Creek and Upper Bear River

TERMINUS MINES, LIMITED

The holdings of Terminus Mines, Limited, are 4,000 feet above sea-
level on the east side of American creek 3 miles above its mouth. The
property was examined by Mr. F. F. Osborne, field assistant, and the fol-
lowing description is derived from his notes. Active exploration began on
this property many years ago and by 1911 preparations were being made to
ship ore. In this year 12 tons of ore were sacked for an initial shipment.
Poor transportation facilities prevented any shipment of ore until 1925.
In the meantime development has been carried out gradually and now
consists of a crosscut adit 370 feet long with short drifts to either side,
a raise to a sublevel 50 feet above the adit, and a shaft 50 feet deep
connecting the sublevel with the surface.

The country rock consists of lava flows and fragmentals of the Bear
River formation, intruded by numerous dykes of various kinds. The vol-
eanic rocks contain much epidote. The dykes consist of feldspar porphyry,
augite porphyrite, diorite, and lamprophyre. Most of the dykes contain
rock fragments and consequently in many places resemble fragmental vol-
canic rocks.

The ore-body is a quartz sulphide vein which follows a shear zone
traversing feldspar porphyry. A post-ore lamprophyre dyke also follows
the shear zone and in some places has been intruded along the centre of
the vein. The vein as revealed in the present workings is in most places
less than 2 feet wide and has been proved to be at least 100 feet long,
but the faces of the drifts are still in it, and it may be much longer.
The ore consists of galena, sphalerite, pyrite, tetrahedrite, and perhaps
silver minerals, in a gangue of quartz. Local concentrations of tetra-
hedrite cause small, rich ore-shoots. Six tons of ore shipped in 1925
ran 260 ounces in silver per ton, 3 per cent lead, and 23 per cent zinc.