Igneous Rock Notes
Read Chapter 4 Section 2 pgs. 98 – 101
Essential Question: How are igneous rocks formed?
Igneous comes from the Latin word that means __fire______.
Origins of Igneous Rock
Igneous rock forms when hot, liquid rock, or _magma____, cools and
solidifies.
Magma can form three ways: 1. __temperature_ 2. _pressure_,
3. ___composition___.
Composition and Texture of Igneous Rocks
_felsic____ __rocks______ are rocks that are light-colored rocks
that are rich in elements such as aluminum, potassium, silicon, and
sodium.
__mafic____ __rock_____ are rocks that are dark-colored rocks
that are rich in calcium, iron, magnesium, and poor in silicon.
Igneous Rocks have different textures depending on how long it takes
for the magma to cool. The ___longer_____ it takes for the magma or
lava to cool, the more time mineral crystals have to grow. The larger
the crystals are the __coarser______ the texture of the igneous
rock.
The __less______ time it takes for magma to cool, the less time for
crystals have to grow. _fine-grained____ igneous rock contains very
small crystals. If it cools fast, it contains _no___ crystals.
Igneous Rock Textures
Felsic
Coarse-grained
Ex. granite
Fine-grained
Ex. Rhyolite
Mafic
Ex. Gabbro
EX. basalt
__intrusive__ igneous____rock_:___ rock formed from the cooling
and solidification of magma beneath the Earth’s surface.
This rock cools very slowly so it has what type or texture?
____________coarse- grained___.
Plutons
are large, irregular-shaped intrusive bodies.
The largest igneous intrusions are ____batholiths__________.
__extrusive_______ igneous_______ rock____ forms from magma
that erupts, or extrudes, and onto the Earth’s surface. It cools quickly
on the surface and contains very small crystals or no crystals.
Identify the examples at the different stations. Look for the texture
and color for clues.
Stations
1
2
3
4
Felsic/Mafic
Coarse-grained/ Intrusive/
Fine-grained
Extrusive