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as they are surrounded by glacial drift, but the magnetite ledges tend to be
elongated parallel to the strike of the limestone, and to occur in three
parallel northwesterly trending belts, an occurrence that is interpreted in
the idealized cross-section.

In many places on the flat top of the ridge, angular fragments of magne-
tite up to a couple of hundred pounds in weight lie strewn along the surface
in such a way as to suggest that they are in reality fractured outcrops. In
addition, small bunches of magnetite occurring here and there within the
limestone could not be mapped; and both of these’ facts point to a wider
distribution of magnetite zones than is shown on Figure 42.

CHARACTER OF THE MAGNETITE

The magnetite is of high quality, medium-grained, steel-grey, hard,
and flagey; small amounts of it show polarity and are classed as lodestone.
Most of it is mixed to some extent with light brown garnet and limestone,
but in several outcrops the gangue is present in amounts less than 30 per
cent by volume.

With the exception of a short stretch of outcrop northwest of open-cut
B, where pyrite is abundant, sulphides are noticeably absent from these
deposits, and very few of the outcrops are rusty.

ORIGIN OF THE DEFOSITS

The deposits are clearly of contact metamorphic origin, being the
result of the replacement of inclined limestone beds by iron solutions
derived presumably from the diorite. All the evidence points to a gradual
replacement of tenuous solutions and not to an ore injection. On polished
surfaces of the magnetite relics of limestone stratification can be seen. The
common occurrence of isolated bunches and grains of magnetite in the
limestone could not be effected by any other means than solutions of very
high penetrating power. Lenticular dyke-like and sill-like masses of magne-
tite occur, but in these also the evidence for replacement can be observed.

In detail, the replacement seems to have taken place along well-defined
stratigraphical horizons, in some cases adjacent to sills of diorite, and this
leads to the inference that further exploration might lead to the establish-
ment of a definite rule of occurrence that would be of the greatest value
in estimating possibilities.

ECONOMIC CONSIDERATIONS
Extent of Deposit

As stated above, magnetite outcrops have been found at intervals
throughout a longitudinal extent of 1,860 feet, and in at least three parallel
zones. The longest continuous exposure is 435 feet along the face of the
bluff, and the longest interval between known exposures is 450 feet. From
the nature of the deposits, there seems to be no reason to suppose that the
magnetite may not continue beyond these limits or that it may not also
occur within the intervals. The difference in altitude between the highest
and lowest outcrops on these claims is 175 feet, but this figure is based on
the heights of different ledges. The greatest vertical exposure on any
single ledge is along the face of the bluff, where mixed magnetite and garnet
are seen from the 260 to the 310-foot contours. Owing to the character of