Headings Metamorphic Rocks Search
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Metamorphic Rocks - Slate, Schist and Gneiss.
Both slate and schist
(pronounced "shist")
are formed from the sedimentary
rocks mudstone and shale.
Mudstone and shale
are formed from compacted mud or
clay.
They are made of very small
flat particles like tiny
plates,
which have often become layered during the sedimentary rock
formation.
Slate.
With additional heat and
pressure,
the rock particles line up in
the same direction (called
"aligning")
and form the rock called slate.
This is an example of low grade metamorphism.
The layered structure (called
"laminated")
allows slate to be easily split into thin
sheets.
You have probably seen dark gray
slate sheets used as roofing.
Schist.
When mudstone or shale
become intensely hot under
pressure,
they may form a new metamorphic
rock called schist.
Schist can be recognized from its thin
layers of interlocking
crystals.
It is harder than slate, and may also be split into thin
sheets.
Gneiss.
The most
common metamorphic rock is gneiss
(pronounced "nice").
Gneiss can be formed from a
variety of rocks
at very high temperatures and
pressures.
It is an example of high grade
metamorphism
and represents the last stage before
melting.
Gneiss is usually named after the
rock it came from
and often shows alternating
layered bands of different minerals.
Headings Metamorphic Rocks Search
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