67

On the Montana claim, a vein striking northeast and dipping north-
west has been traced on the surface for 300 feet. The vein is less than a
foot wide, consists of quartz mineralized with pyrite, sphalerite, galena,
and tetrahedrite and contains high-grade silver ore. It has been developed
by short drifts and a shallow winze driven from a crosscut adit. <A total
of 21 tons of ore averaging $200 in gold, silver, and lead was shipped from
the winze and drifts in 1913 and 1915. A few hundred feet northeast of
the adit another crosscut adit has been driven to intersect the vein, but
has not been driven far enough. Farther up the hill a drift adit 180 feet
long follows a different vein and an associated dyke for 60 feet. The
vein is vertical and strikes northeast. It is 3 feet wide at the portal, but
narrows rapidly and pinches out. It consists of quartz mineralized with
pyrite, galena and sphalerite, and tetrahedrite. A short ore-shoot 1 to 2
feet wide is present at the portal of the adit. An assay of a sample
representing one foot of the width of the ore-shoot showed 85 ounces
silver per ton, 14 per cent lead, and 21 per cent zinc.

Recent development has been concentrated on a different type of
mineral deposit in a bed of limestone. The bed has been offset by two
faults into three blocks each several hundred feet long. The faults strike
north 60 degrees east and dip 50 degrees northwestward. Mineral deposits
have been found in the upper block of limestone. The fault between the
middle and upper limestone blocks is mineralized and consequently the
fault is probably pre-mineral. ‘The limestone is sheared parallel to the
strike, and where argillaceous matter is present shear planes are quite
distinct, but where the limestone is pure the whole has been changed to
marble with no visible shear planes. Rusty mineralized zones strike
northwestward in the upper limestone block. The width of the zones
varies from 1 to more than 20 feet.

The rusty mineral zones contain chiefly sphalerite and minor amounts
of pyrite, galena, and chalcopyrite. The boundaries of the mineralized
areas are quite indefinite, and as development is not extensive, the exact
size and shape of the mineral bodies are not known. The deposits may
represent replacements along limestone beds or along shear zones. If a
favourable bed outcropped at various places on the surface and dipped
down hill it would present a broad outcrop in some places and a narrow
one in others. The variable width of the deposits suggests a replaced bed
rather than a replaced shear zone.

Mineral deposits in general that are formed by replacement of lime-
stone are as a rule of extremely irregular shape, and consequently if they
are to be clearly outlined development work must be extensive.

WASHINGTON GROUP

The Washington group is at an elevation of 3,800 feet on the south
side of the south fork of Marmot river. The country rocks are lava
flows, tuffs, and breccias of the Bear River formation, underlain on the
lower part of the property by argillites of the Bitter Creek formation.
The sediments and volcanic rocks strike northwest and dip northeast at
moderate angles. The batholith contact passes less than a quarter of a
mile west of the adit.