213
CROYDON GROUP (8)

Reference: Lay, Douglas: Aiken Lake Area, British Columbia ; B.C. Department of
Mines, Bull. No. 1, pp. 8-19 (1940).

The Croydon group of claims lies about 9 miles by trail from the west
end of Aiken Lake on the lower part of Croydon Creek, a tributary of
Kliyul Creek. The claims are owned and were explored by The Con-
solidated Mining and Smelting Company of Canada Limited. Operations
ceased when the camp was destroyed by forest fire in 1938. At present,
six claims are held in good standing.

The deposits lie in nearly parallel, steeply dipping shear zones in
medium-grained hornblende diorite. The shear zones vary in width from
a few inches to about 30 feet, and contain lenticular bodies of vein quartz,
usually with free walls. The individual quartz bodies are seldom more
than 2 feet wide, but an interlacing network of them, separated by thin
partings of sheared altered hornblende diorite, in many places occupies the
entire width of the shear zone. The sheared hornblende diorite has been
largely altered to a soft, green, chloritic material, which in places is prob-
ably antigorite serpentine.

The quartz is irregularly mineralized with massive to crystalline pyrite
and chalcopyrite. Metallic minerals do not comprise more than about 5 per
cent of most of the veins examined, but local concentrations of almost
solid sulphides form lenses up to 2 feet wide and 15 feet long. Small
amounts of magnetite, molybdenite, gold, and an unidentified soft, silvery
mineral accompany the pyrite and chalcopyrite. The ore minerals are
confined mainly to the quartz bodies, but in a few places the sheared
hornblende diorite is pyritized. Later fractures cutting through the quartz
and the ore minerals have been filled with a cream-coloured carbonate
mineral, probably calcite.

Exploratory work has been concentrated on four, quartz-filled shear
zones that lie within a belt 250 feet wide on the southwest side of Croydon
Creek (See Figure 14). Each of the shear zones strikes about north 10
degrees east and dips steeply southeast. The two most easterly of these
shear zones are actually parts of the same broader shear zone, and are
separated by 5 to 20 feet of sheared rock containing small, erratically
distributed quartz lenses. The eastern part of this broad zone is known
by the owners as ‘vein No. 13’, and is visibly mineralized for a length of
270 feet. As its northernmost exposure, the ‘vein’, or quartz-rich part of
the shear zone, is 6 feet wide and contains an aggregate width of 4 feet
of rusty, fractured, sparsely mineralized quartz. A sample across 54 feet
at this point assayed: gold, 0-03 ounce a ton; silver, 0:18 ounce a ton;
and copper 0-01 per cent. Southward from this point ‘vein No. 13’ pinches
and swells, and the vein matter consists of a series of lenticular quartz
stringers and veinlets, with an average total width of about 2 feet. In
places it is abundantly mineralized. A sample of almost solid, massive to
granular pyrite from the dump, very similar to that found at, and believed
to be from, the central part of this ‘vein’ assayed: gold, 0-105 ounce a
ton; silver, 0-70 ounce a ton; and copper, 0-32 per cent. At the point
farthest south on ‘vein No. 13’ penetrated by underground workings, the
quartz-rich part of the shear zone is more than 10 feet wide. A sample