Download Igneous Rocks

Aim: How are rocks classified?
Do Now:
In your notes answer the following questions.
1) What do you think rocks are made of?
2) How do you think scientists classify rocks?
3) Can you think of any situation in which you have
used rocks in your daily life?
• Rocks are made of one or more common minerals.
- rocks made of one mineral are monominerallic
• Rocks are classified based on their origin (how
they are made).
There are 3 common types of rocks:
1) Igneous
2) Sedimentary
3) Metamorphic
I. Igneous Rock:
• Igneous means “fire”
• come from magma or lava (hot material) that
crystallizes into rock.
- Magma is found below the crust (Inside
the Earth)
- Lava is found on top of the crust
(Outside the Earth)
II. Environment of Formation
A. Intrusive (plutonic) –
magma cools/hardens beneath Earth’s
surface slowly.
•cooling slowly
allows the minerals
to grow into large
crystals in the rock
causing a coarse
texture.
Granite
B. Extrusive (volcanic) –
lava cools/hardens above the Earth’s surface
quickly.
•cooling quickly
stops the minerals
from growing in the
rock and creates
fine, glassy and
vesicular textures.
Rhyolite
III. Textures
- Coarse (large) crystals
- Fine (small) crystals
- Glassy (no crystals)
- Vesicular (gas pockets)
Granite
Pumice
Obsidian
Rhyolite
IV. Other Characteristics
• Color is described as light or dark
• Density is described as high or low
• Composition is described as:
- Mafic: containing Iron (Fe) and Magnesium (Mg)
- Felsic: containing Silicon (Si) and Aluminum (Al)