143

The value of the vein matter depends on its lead and silver content.
Clothier has estimated the average lead content at 20 per cent and states
that specimens containing 77 per cent lead assay 16-8 ounces in silver.

The chalcopyrite replacement deposit outcrops at an elevation of 2,900
feet. The rocks in the neighbourhood of this deposit are approximately
horizontal, fragmental, volcanic rocks and possibly lava flows, and an
interbed of argillite. Chalcopyrite is disseminated through the argillite
and to a lesser extent through the immediately overlying volcanic rock.
The upper part of the argillite bed contains more copper than the lower
part. The size and shape of the mineralized area are not clearly outlined
and the geological structure is not clearly understood. The bed of
argillite is evidently offset by two normal faults with in each case the
downthrow on the east side. A narrow streak of clean chalcopyrite lies in
one of these faults, showing either that the faults are pre-mineral in age
or that faulting took place between an early and a later period of
mineralization.

A crosscut adit 150 feet below the outcrop of the mineral deposit
crosses a body of pyrite and chalcopyrite 5 feet wide at 212 feet from the
portal and enters a body of chalcopyrite near the face. The body nearest
the portal is vein-like, strikes at right angles to the direction of the adit,
and dips 65 degrees toward the face. This body has not been found on the
surface. The mineralization near the face of the adit is in argillite and in
overlying volcanic rock, and is of the same type as that in the argillite on
the surface. It is assumed that this is the same bed of argillite as out-
crops on the surface, and that it was downthrown to its present position
by a fault. According to this idea the mineralization follows the argillite
bed and conforms rather closely to the strike and dip of the rock formation
which is gently dipping and striking at right angles to the adit.

Roosevelt Group (Locality 63)

References: Annual Report of the Minister of Mines, British Columbia, 1904, 1906,
1909, and 1910; Geol. Surv., Canada, Memoir 32.

The Roosevelt group of claims is on the north fork of Bitter creek
‘about a mile above its mouth. The country rock of argillite is intruded
by many dykes and the main mineral deposit is beside a dyke. The deposit
is about 5 feet wide and consists of crushed and silicified argillite carrying
pyrite, chalcopyrite, and galena. The main values are probably in silver
and lead but samples have assayed as much as 0°28 ounce in gold a ton.

Royal Irish Group (Locality 56)

Reference: Annual Report of the Minister of Mines, British Columbia, 192U.

The Royal Irish group is in Bear River valley between Bitter and
Fitzgerald creeks. Large bodies of quartz in granodiorite contain low
values in gold.

88465—103