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textural or mineralogical features can be observed in hand specimens, but
the less altered parts show a wide variety of grain sizes and textures.
Almost all are relatively coarse grained, with crystals from 4, inch up
to 2 inches or more long. Most of the rocks are composed mainly of
rounded, anhedral grains with a seriate texture; but in parts of the stock
east of Polaris Creek where textural differences have not been obliterated
by serpentinization, there is a distinct variety consisting largely of crystals
of pyroxene 2 to 5 inches long. The large crystals are markedly poikilitic,
including numerous rounded individual grains and reticulated networks
of grains of olivine up to + inch in diameter. On outcrops and in hand
specimens these coarse peridotites may be recognized by the reflection
of light from similarly oriented cleavage surfaces, which show the presence
of skeletal pyroxene grains that are otherwise very difficult to distinguish.
Some of the rocks of this type appear to have very little groundmass; the
whole rock seems to be an aggregate of coarse, poikilitic pyroxene crystals,
and essentially all the olivine, which may comprise much more than half
the rock volume, occurs as inclusions in the pyroxene. In other varieties,
the large poikilitic pyroxene grains are scattered through a finer grained
matrix; in places, clusters of olivine grains in the matrix have been com-
pletely serpentinized and, on exposed surfaces, largely removed by erosion,
so that outcrops of this rock have a distinctive pock-marked appearance,
with more or less equidimensional pits up to 2 inches in diameter and
2 inches deep, spaced two or three to the square foot.

In general the olivine-rich peridotites are finer grained than the rocks
containing more abundant pyroxene. Many of these rocks show a type
of glomeroporphyritic texture, with clusters of relatively large pyroxene
grains in a granular, pyroxene-free olivine matrix. In some rocks of this
type the texture seems to be porphyroclastic, with the more easily crushed
olivine suffering a greater degree of granulation than the pyroxene.

Rocks that appear in hand specimen to contain only granular olivine
have the equigranular, sugary texture and, when fresh, the pale olive-green
colour common to dunites. Dunites (peridotites containing more than
95 per cent olivine) are probably rare in these rocks, at least in those
sufficiently fresh to enable their minerals to be determined; but peridotites
containing more than 85 per cent olivine are widely distributed, and
constitute perhaps one-fifth of the area of the relatively fresh ultramafic
rocks exposed east of Polaris Creek. A typical variety of this rock con-
sists of elliptical clusters up to 3 inches in diameter of relatively coarse
pyroxene grains scattered at intervals of 1 foot to 3 feet in a granular
matrix consisting almost entirely of olivine. It may be that dunite was
relatively more abundant in those parts of the stock now more completely
serpentinized for, in general, the olivine-rich peridotites are more altered
than those containing less olivine. The dunite and olivine-rich peridotite
occur characteristically in irregular bodies a few tens or at most a few
hundreds of feet in greatest dimension. No systematic form of the bodies
or pattern of their distribution could be recognized. In many individual
outcrops the olivine-rich bodies seem to be roughly tabular, but when the
contacts were carefully followed the bodies were invariably found to be
completely irregular and haphazard in outline.