135

. DESCRIPTION OF ORE OCCURRENCES

| The ore outcrops examined are confined to the summit of Iron Range
| mountain and the head of Thompson creek. They are, for the most part,

artificial exposures made years ago and are separated from one another

by drift-covered stretches. The exposures are usually limited in extent

and none shows the full width of the mineralized rock. They consist of
| country rock impregnated with hematite and quartz in varying pro-
portions and quantities. In places the hematite forms nearly pure bodies
4 to 20 feet thick, but of unknown length and depth. The hematite is
usually compact, very fine-grained, minutely scaly, but in part, where it
has been subjected to stresses, it is more micaceous and is traversed by
closely spaced, lustrous, parting planes. A small amount of magnetite is
present in some places. As a rule little or no pyrite or other sulphide is
visible. The country rock is usually quartzite, but in places dykes of
igneous rock are involved and in several localities the mineralization seems
to have extended into the sills.

The individual ore outcrops have an irregular banded structure dip-
ping vertically or at very high angles to the west and striking in a general
way north and south. The banded structure where best developed is due
to a succession of zones of varying widths and compositions. In some the
material is largely country rock impregnated or seamed and filmed with
hematite or quartz or both these minerals. Others are largely of hematite
or of hematite and quartz. In the several instances where considerable
breadths of wider mineralized areas are visible, the amount of mineral-
ization is at a maximum close to one edge of the exposure and, on the whole,
gradually decreases in amount in the direction of the other edge.

The ore outcrops on Iron Range mountain succeed one another within
a strip of country 6 miles long and 1,800 feet broad. The structures of the
individual exposures parallel the general trend of the whole series of out-
crops and this and other phenomena have led various observers to assume
that the isolated, mineralized outcrops belong to a few parallel zones each
extending for a comparatively long distance and, in some cases, marked
by an intermittent or perhaps continuous border of high-grade hematite
ore. There is direct evidence that individual mineralized zones are as
much as several hundred yards in length and possess fairly uniform characters
over such lengths. But there is no evidence indicating whether the indi-
vidual zones are few or many, are relatively long or short, or whether the
bodies of relatively pure hematite are short or of considerable length.

The positions of the ore outcrops seen on Iron Range mountain are
indicated on Figure 24; possibly other unnoted outcrops are present, but
there is no reason to believe there are many such. The three most north-
erly outcrops lie at the north end of the ridge within a breadth of 300
yards across the strike. The most westerly showing is on the Golden Cup
claim where a tunnel has been driven south-southwest for, judging from
the size of the dump, 50 feet or more. Forming the east side of the entrance
to the tunnel is a 12-foot rock face of dark igneous rock, presumably a
dyke. This rock is seamed with narrow veins of quartz and veinlets of
hematite and holds many minute crystals of magnetite in the immediate
vicinity of the veins. West of the igneous body the strata appear to be
altered quartzite bleached white and comparatively soft. It is veined,
seamed, and impregnated with quartz and hematite in amounts diminishing