Igneous Rocks

• The students will be able to identify different
minerals, colors, sizes, and textures that
appear in most intrusive igneous rocks.
• The word igneous comes from the Latin word ignis,
which means "fire".
• Igneous is used to describe rocks that crystallize out
of hot molten material in the Earth called magma.
• When magma pushes up through Earth's crust to
the surface, it is called lava. Both magma and lava
cool and harden to form igneous rocks.
Intrusive = In
• Made from magma.
• Cools inside the Earth.
• Cools slowly, allowing
large crystals to form.
• Crystals can usually be
seen by the unaided eye.
Extrusive = Exit
• Made from lava.
• Cools on the Earth’s
• Cools quickly, forming
small crystals.
• Need a magnifying devise
to see crystals.
Types of Minerals
1.) Felsic Minerals
• They are light in color
• Colors include: gray, white, pink,
or colorless
• They have more silica than any
other mineral 65%+
2.) Intermediate Minerals
• Darker than Felsic, but lighter
than Mafic
• 55%-65% of the mineral is silica
• Granodiorite (Granite)
3.) Mafic Minerals
• Darker minerals
• Colors include: black, brown,
dark gray, or green
• They have a lot of iron and
magnesium in them
4.) Ultramafic Minerals
• Dark colors and can have some
• Less than 45% silica
• Has lots of iron and magnesium
in them
How can you tell how many minerals are in a rock?
Just by looking at them!
Physical Characteristics
Intrusive rocks have
large crystals that can
be seen with the naked
A rock with large crystals
is coarse-grained
Physical Characteristics
Igneous intrusive rocks can
Felsic (Light colored)Minerals are often colorless,
white, gray or pink
Mafic (Dark colored)Minerals are chiefly black,
brown, dark gray and
sometimes green
Other Important Intrusive Rocks
• This rock is the equivalence of a Basalt which is in
extrusive rocks.
• Coarse grained rock
• Medium coarse grained rock
• How are they made?
• When molten magma is stuck underneath the Earth’s
surface, it begins to cool and crystallize.
Building materials
Counter tops (kitchens,
Curling stones-Thick stone disc
with handle (40lbs.) used for a
sport played on ice.
• Gabbro. (2010, December 3). Retrieved January 23, 2011,
from Wikipedia: http://en.wikipedia.org/wiki/Gabbro
• Granite. (2011, January 18). Retrieved January 23, 2011,
from Wikipedia: http://en.wikipedia.org/wiki/Granite
• Hamilton, C. &. (2011). Igneous Rocks. Retrieved January
23, 2011, from scienceviews.com:
• Vogel, C. G. (2000). Science Explorer Inside Earth. Upper
Saddle River, New Jersey: Prentice Hall.
• Galleries, A. (2011, January 21). The Rock. Retrieved
January 18, 2011, from Amethyst Galleries:

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