93

The feldspar varies greatly in habit, occurring in some rocks as
interstitial, stringy masses, and in others as rounded grains with sutured
borders, or as small subhedral erystalloblasts. Two distinct kinds of feld-
spar are represented; albite-oligoclase, and potash feldspar—both ortho-
clase and microcline. In the less metamorphosed quartzites, which usually
contain less than 30 per cent total feldspar, nearly all the feldspar recog-
nized was found to be plagioclase, much of which shows polysynthetic
albite twinning. Many of the plagioclase crystals are zoned, and are
commonly clouded by fine dust-like inclusions. In more highly feldspathic
rocks, which seem to be also coarser and better crystallized, grains of
orthoclase appear, and in some sections comprise an estimated 10 per cent
of the rock. At higher metamorphic grades, where the rock passes into a
quartz-mica-feldspar gneiss, a few crystalloblasts of microcline were
observed, but microcline and orthoclase were not both noted in the same thin
section of any of the rocks classed as quartzites.

The foliation of the quartzites is due primarily to the flakes of biotite,
which in some sections appear to have a nearly perfect planar arrange-
ment. In general, there is no sign of linear structure, and thin sections
parallel with the foliation plane show a haphazard pattern of grains. The
muscovite shows much less tendency toward a common planar orientation
than the biotite, and some relatively large grains have grown with their
long axes across the foliation. In many specimens the quartz and feldspar
grains are elongated and share in the general foliation.

Needles of sillimanite, commonly grouped in radiating clusters, were
observed in about half the thin sections examined, the largest noted about
a millimetre long. Most of them are in the biotite flakes; although a
few crystals of what appears to be the same mineral occur in quartz.

Quartz-mica-feldspar Schist

The quartz-mica-feldspar schists of the Wolverine complex differ in no
essential respect, except in the proportion of quartz, from the feldspathic
quartzites with which they are interbedded, and which themselves are
either schistose or gneissic. Rocks in which quartz is not a dominant
mineral are quite minor, and in the main are restricted to beds, usually
less than 3 feet thick, that are correspondingly richer in biotite. Although
most of them probably represent beds that were originally among the
most fine-grained beds in the assemblage, many are now slightly coarser
in texture than the quartzites with which they are interbedded, indicating
that they recrystallize with greater ease than the quartz-rich rocks.

Garnetiferous Schist and Quartzite

Garnet-bearing rocks are of relatively restricted occurrence in the
Wolverine complex. The abundant quartz-mica-garnet schists of the
Tenakihi group apparently suffer a complete breakdown of garnet during
alteration to quartz-mica-feldspar schists and gneisses.

The Ingenika group rocks exposed in the syncline passing through
Tomias Lake Valley have been metamorphosed to quartz-muscovite-
garnet schists and quartzites, and garnet-bearing quartzitic conglomerates,