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The rock on the Ferguson property is blue-grey to cream-coloured
crystalline limestone of the Ingenika group of Lower Cambrian age. In
the vicinity of Fergusons Hill the limestones are in part intensely contorted,
and in place are converted into a schistose rock containing much sericitic
material.

In most parts of the property the bedding strikes about north 80
degrees west and dips northerly at 20 to 40 degrees. The beds outcropping
on the west end of the hill have been partly to completely silicified and
show all gradations from relatively pure limestone to white quartz rock.
Subsequent to silicification, the limestone was attacked by iron carbonate
solutions. In the highly silicified, finely bedded rock, siderite was deposited
along the bedding planes so that the rock now consists of parallel lamin of
white quartz, y inch to 2 inches thick, separated by layers of dense, brown
siderite. In the most heavily mineralized parts quartz and siderite are in
about equal proportions. In places it is possible, within a distance of
100 feet, to trace the changes along a single bed from blue-grey crystalline
limestone to greyish white massive quartz rock, with faint traces of original
bedding, to banded, quartz-siderite rock. In the slightly silicified lime-
stone, and to a lesser extent in the highly silicified, massively bedded rock,
the siderite is not confined to bedding planes but forms large, irregular
masses up to 20 feet in diameter of very coarsely crystalline, nearly pure
mineral.

Replacement of the quartz-siderite rock by pyrite, sphalerite, and
galena, with lesser amounts of copper and silver sulphides, has resulted
in the formation of distinct mineralized zones, which in general follow the
bedding. A little sulphide mineralization is also in evidence along joint
planes. The four most prominent mineralized zones have been explored by
stripping and underground workings (See Figure 18).

The lowest zone, known as No. 1 zone, outcrops only at the west end
of the southward-facing cliffs that form the crest of the hill. There a
body of coarsely crystalline galena 1 foot to 2 feet thick occurs in a 20-foot
band of contorted quartz-siderite rock. Where fractured, this rock con-
tains a little pyrite and sphalerite. It has retained the original bedding
structures of the limestone that it has replaced, and appears entirely con-
formable with the overlying and underlying unmineralized limestone. The
galena body lies about 6 feet above the base of the quartz-siderite band,
and is overlain by 1 foot to 3 feet of crystalline siderite heavily mineral-
ized with pyrite and, in places, with sphalerite.

Although much deformed in detail, the quartz-siderite rock and the
included galena body nevertheless show a uniform, over-all strike of north
70 degrees west, and dip 25 to 40 degrees northeast. The contacts of the
mineralized zone are sharp, and in every observed case are parallel with
the bedding.

What is believed to be the No. 1 mineralized zone was encountered in
crosscuts from No. 4 adit, 80 feet south of the portal (See Figure 13).
There it appears as discontinuous, lens-shaped bodies of siderite, sphalerite,
and galena up to 4 feet thick lying conformably along the same horizon
in well-bedded, slightly silicified, blue-grey limestone underlain by sheared
sericitic limestone.