Transcript Igneous Rocks

Igneous Rocks
Sample Pictures of Different
Igneous Rocks and their
Textures
Course Grained
Granite- Formed from the slow cooling
of magma. Large crystals form.
Uses of Granite
Granite is used for long lasting
monuments and for trim and
decoration on buildings.
Fine Grained
Rhyolite- Formed from the rapid
cooling of magma. Very small crystals.
Uses of Rhyolite
Rhyolite is used as an aggrigate.
Porphyritic
Rhyolite Porphyry- formed from unequal
or mixed cooling of lava. Larger
crystals on a background of smaller
crystals
Porphyritic
Granite porphyry- formed from unequal
or mixed cooling of lava. Larger crystals
on a background of smaller crystals
Glassy Texture
Obsidian-result of instantaneous cooling of
the lava.
Vesicular
Pumice-full of tiny holes due to gas
bubbles that were trapped inside when the
lava cooled.
Uses of Pumice
Because it is so light, pumice is often used
as a decorative stone in gardens.
When ground up into a powder, Pumice is
used as an abrasive in polishing
compounds.
Pumice is also found in Lava soap.
Intrusive vs. Extrusive
Intrusive Igneous
Rocks- Form on the
inside of the earth’s
crust from magma.
Typically have larger
crystals due to the
slower rate of
cooling.
Extrusive Igneous
Rocks- Form on the
earth’s surface from
lava. Typically have
smaller crystals due
to the more rapid
rate of cooling.