Igneous Intrusive Rocks

Objectives

• The students will be able to identify different minerals, colors, sizes, and textures that appear in most intrusive igneous rocks.

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 vs. Extrusive

• Made from magma.• Cools inside the Earth.• Cools slowly, allowing large

crystals to form.• Crystals can usually be seen

by the unaided eye.

• Made from lava.• Cools on the Earth’s surface.• Cools quickly, forming small

crystals.• Need a magnifying devise to

see crystals.

Intrusive = In Extrusive = Exit

Granite Obsidian

Types of Minerals

How can you tell how many minerals are in a rock? Just by looking at them!

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 them4.) Ultramafic

Minerals• Dark colors and can have

some green• Less than 45% silica• Has lots of iron and

magnesium in them

Physical Characteristics Intrusive rocks

have large crystals that can be seen with the naked eye.

A rock with large crystals is coarse-grained

Physical Characteristics

Igneous intrusive rocks can be….

Felsic (Light colored)- Minerals are often colorless, white, gray or pink

And

Mafic (Dark colored)- Minerals are chiefly black, brown, dark gray and sometimes green

Other Important Intrusive Rocks

Gabbro • This rock is the equivalence of a Basalt

which is in extrusive rocks.• Coarse grained rock

Granite • Medium coarse grained rock• How are they made?• When molten magma is stuck underneath

the Earth’s surface, it begins to cool and crystallize.

Uses of Igneous rocks

Building materials Counter tops (kitchens, bathrooms)

Tiles Tombstones

Roads Jewelry

Curling stones-Thick stone disc with handle (40lbs.) used for a sport played on ice. Marbles

Works Cited• 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: http://www.scienceviews.com/geology/igneous.html

• 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: http://www.galleries.com/rocks/granite.htm

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