38

apparently as a result of merging with the granite. This evidence and
also the fact that locally the granite contains disseminated molybdenite
suggests strongly that the veins and the molybdenite were derived from
the body of granite during its consolidation. Dolmage! examined the
veins in 1922 and states that approaching the intrusive body they change
gradually from quartz veins to aplite dykes. The average grade of the
ore is probably less than 2 per cent molybdenite, but the ore is very free
from other sulphides such as pyrite. The veins are up to 10 feet wide
but the tonnage of available molybdenite is not great unless the veins
show a marked improvement in depth.

The second deposit characterized by molybdenite disseminated in
dykes and a small body of granite has not been explored sufficiently to
permit estimating grade or tonnage.

QUARTZ VEINS CONTAINING ONE OR MORE OF THE METALS, SILVER, LEAD,
AND ZINC

Quartz veins of this group are practically restricted to the south-
western quarter of Alice Arm district. About twenty-five such veins have
been opened sufficiently to show the type of mineralization. All cut
sedimentary rock which at most properties consists of black argillites
interstratified with argillaceous quartzites. Some veins, as for example
the LaRose vein, are of good size and persist only where they penetrate
the harder, competent beds. Others, like the Wolf and Esperanza veins,
are of value where they cut argillite, and still others such as the main
Esperanza vein are largest and richest where they have a certain attitude
or structure. Some of the veins adjoin narrow lamprophyre dykes, as is
the case of the Silver Chord and Wolf veins.

The veins are in general less than 6 feet wide and most of the well-
mineralized veins are less than 3 feet thick. Some quartz veins in the
area are barren of sulphides and one of these on the Macy claim was
mined for a short time by the Granby Consolidated Mining and Smelting
Company as flux for their smelter at Anyox. Most of the quartz veins
contain some sulphide, chiefly pyrite, some of them contain silver miner-
als such as the ruby silvers and argentite and have been mined as silver
ore. Most of the silver-bearing quartz veins also contain some lead and
zinc sulphides. Some of the veins contain galena and sphalerite and no
silver. A few contain small quantities of scheelite.

Only three of the veins have produced ore and, therefore, sufficient
information to formulate any general conditions governing the formation
of ore shoots is lacking. The LaRose ore shoots occur only where the
country rock fractured readily and thus gave rise to larger openings. In
the Esperanza vein the richest and largest ore shoots lay along the apex
of the gently plunging anticlinal form that has been assumed by the
vein.

*“ Coast and Islands of British Columbia between Douglas Channel and the Alaskan
Boundary”; Geol. Surv., Canada, Sum. Rept. 1922, pt. A, p. 31.