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Schist
A metamorphic rock having a strong planar structure called schistosity
resulting from the parallel orientation of platy minerals, such as mica,
chlorite and talc.
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A planar foliation or schistosity defined by biotite, quartz and
feldspar is represented in the photograph on the left. The eye-shaped
(augen) red garnet crystals are called porphyroblasts. A widely-spaced,
mineral banding, defined by light and dark bands, indicate that the rock
also has a gneissic component (see Gneiss). This sample comes from the
Port aux Basques area.
The photo on the right shows staurolite
crystals, called porphyroblasts, in a mica schist. Note the small quartz
vein in the upper right-hand corner. This sample comes from the Bay
d'Espoir area.
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Amphibolite
A metamorphic rock consisting of mostly amphibole and plagioclase feldspar.
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A folded mafic dyke, in this photo, has been metamorphosed to mostly
amphibole (hornblende) and plagioclase; it cuts across marble derived
from limestone. (Rigolet, Labrador).
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Gneiss
A coarse-grained metamorphic rock with a banding (gneissosity) produced
by alternating layers of light and dark materials.
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The gneissic banding produced by alternating layers of light and dark
minerals comes from the Postville area of Labrador. The banding is not
sedimentary, but is due to metamorphism.
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Migmatite
A mixture of old metamorphic (dark) and new igneous granitic (light)
material caused by the interlacing of thin veins and stringers of
granitic material with metamorphic rocks.
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Dark, biotite-rich metamorphic rocks in a medium-grained, light coloured
granitic rock containing quartz and feldspar. This photo is from the
Spruce Pond area, on the Burgeo Road.
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