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Most of the amphibolites contain some biotite, and a few rocks are
composed almost entirely of hornblende and biotite. The biotite occurs in
elongate, deeply coloured, pleochroic grains that are in part interstitial to,
and in part transect, the hornblende crystals, suggesting that it may, in
part, have crystallized later than the amphibole. Minor minerals in the
amphibolites include quartz, which is relatively rare but occasionally
found as very large, poikilitic masses; apatite, which is relatively abundant
as spindle-shaped to prismatic grains up to 4 mm. long; and accessory
zircon, magnetite, and pyrrhotite.

S fy I [oe as amphibolite

Talus

Leucogranite

Eley. 5600’

Approximate scale along crest of ridge, 1 inch to 90 feet

Figure 5. Sketch, looking northwest, of part of the roof of the granodiorite stock
exposed on the southwest shoulder of the mountain east of Blackpine Lake.
Like the skarns and silicated marbles, the amphibolites are considered

to have resulted from the alteration of limestone beds of the Ingenika
group. The development of hornblende-feldspar gneiss and amphibolite
from limestone by the action of granitic intrusions is a well-known pheno-
menon (Adams, 1909; Barth, 1930). The process involves the supply of
silica, alumina, iron and magnesium oxides, and alkalis to the limestone by

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