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The most important mineralized zones explored to date are Nos. 2 and 3.
They are well exposed at the west end of the summit of Fergusons Hill,
and are explored by Nos. 1, 2, and 4 adits. These zones form two parallel
bands, 3 to 10 feet wide, heavily replaced by sulphides, and separated by 1
foot to 8 feet of poorly mineralized rock lying near the middle of a series
of beds, with a total stratigraphic thickness of 50 feet, that has been intensely
silicified and irregularly replaced by siderite. The base of No. 2 mineralized
zone lies about 30 feet stratigraphically above the No. 1 zone.

The series of beds in which Nos. 2 and 3 mineralized zones are found
is much contorted, but an over-all uniformity of attitude can be traced, and
mineralization seems to have taken place at the same stratigraphic intervals
throughout. Wherever observed, the contacts of the sulphide bodies are con-
trolled to a minute degree by the contorted bedding planes of the host rock.
As with No. 1 mineralized zone, the most concentrated mineralization has
occurred close to the beds that have suffered the most intense silicification,
but separated from them by 1 foot to 5 feet of quartz-siderite rock contain-
ing a relatively higher proportion of siderite.

The highest mineralized zone, No. 4, lies about 25 feet stratigraphically
above the top of No. 3 zone. It outcrops on the summit of the hill, and can
be traced down the north slope to the portal of No. 2 adit. The most
heavily mineralized body in this zone is from 2 to 8 feet thick. The rocks
in which the sulphide body of No. 4 zone is found are highly silicified, but
contain relatively less siderite than the host rocks of Nos. 1, 2, and 3 zones.

The mineral composition of all four zones is remarkably uniform.
Mineralographic study! has indicated the presence of the following minerals,
arranged in order of deposition from earliest to latest:

quartz

siderite

arsenopyrite

pyrite

pyrrhotite

magnetite (may be earlier)
sphalerite

chalcopyrite

tetrahedrite (variety freibergite)
galena

pyrargyrite

siderite (and calcite?)

Subsequent, supergene alteration has developed considerable limonite,
and minor amounts of marcasite, covellite, and malachite.

Sphalerite and galena together constitute more than 90 per cent of
the metallic minerals. Pyrite is locally plentiful in bodies up to 2 feet
thick, immediately overlying, and replaced by, galena and sphalerite. The
only silver-bearing minerals recognized as such, argentiferous tetrahedrite
and pyrargyrite, were found to be much more abundant in pyrite-rich
specimens than in specimens consisting chiefly of sphalerite or galena. No
silver minerals have been identified in specimens of crystalline galena,
although spectrographic analyses of apparently pure galena show a moder-
ate silver content.

1The writer is indebted to Mr. E. Lea for assistance in the laboratory investigation of material
from this deposit.