Identifying Rocks
Igneous Rocks - Formation
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Magma is ejected
from earth’s core
Crystals form in
cooling magma
Crystals interlock into
masses known as
igneous rocks
Igneous Rocks - Identification
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the interlocking texture of
the grains
the presence of vesicules
(holes) in extrusive
igneous rocks
may be dark-colored and
heavy
may display two grain
sizes, one much larger
than the other
Sedimentary Rocks - Formation
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Other rocks (igneous,
metamorphic) or
shells are weathered
over time
Can be formed from
compaction of these
sediments
…or can be formed
by crystallization of
dissolved minerals
Sedimentary Rocks - ID
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grains cemented together
the presence of fossils
light-colored and light
weight
may display interlocking
grains but is very light
weight
Layers!
Metamorphic Rocks - Formation
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“Metamorphosis” =
change
Sedimentary or
Igneous Rocks that
have been changed
by intense heat or
pressure
Metamorphic Rocks - ID
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the interlocking
texture of large grains
foliation (layering) layers likely “bent”
banded light and dark
colors