Igneous Rocks

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Igneous Rocks 6th Grade Science
Mrs. PancakeSummer 2003
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How are they formed?
Lava
Magma
So, Whats the difference?
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Lava
Magma

• Magma molten material inside the earths
  surface.
• Lava molten material outside the earths
  surface.

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Intrusive Rocks
Magma
Gabbro Diorite
Granite Peridotite
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When magma underneath the surface cools,
Intrusive Rocks are formed. They cool slowly,
allowing visible crystals to form.
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Texture
Large,Visible Crystals Coarse-Grained
Close up of Granite
Close up of Diorite
Coarse-grained texture can also be called
phaneritic texture.
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Extrusive Rocks
Lava
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When the lava from a volcano cools and hardens,
Extrusive rocks are formed. The lava cools too
quickly for visible crystals to form.
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Texture
1. Very rapid cooling a. No Crystals---Shiny---Gla
ssy b. No Crystals---Holy---Vesicul
ar rapid gas escaping
Close-up of Obsidian
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Texture
Close-up of Basalt
2. Quick Cooling a. Small crystals---fine grained
Close-up of Rhyolite
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Credits
Magma image http//www.iss.k12.nc.us/schools/em
s/falcons/Goldrick20Science/Igneous20Rocks.htm
Granite image http//sln.fi.edu/fellows/payton/r
ocks/expert/granite.htm Lava image
http//www.zero-kelvin.com/hi02/000204.php

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Diorite image http//geology.csupomona.edu/alert
/igneous/iddiorite.htm Gabbro image http//geolo
gy.csupomona.edu/alert/igneous/idgabbro.htm Perid
otite image http//geology.csupomona.edu/alert/ig
neous/idperidotite.htm Magma image
http//pubs.usgs.gov/gip/volc/types.html Phanerit
ic texture image http//geology.csupomona.edu/ale
rt/igneous/texture.htm
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Close-up of Rhyolitehttp//www.geolab.unc.edu/Pe
tunia/IgMetAtlas/volcanic-micro/rhyolite.X.html Cl
ose-up of Basalthttp//www.geolab.unc.edu/Petuni
a/IgMetAtlas/volcanic-micro/vesicles.X.html Close
up of Obsidianhttp//www.geolab.unc.edu/Petunia/
IgMetAtlas/volcanic-micro/vitrophyre.X.html Close
up of Dioritehttp//www.geolab.unc.edu/Petunia/I
gMetAtlas/plutonic-micro/sieve.X.html Close up
of Granitehttp//www.geolab.unc.edu/Petunia/IgM
etAtlas/plutonic-micro/poikilitic1.X.html