Download Igneous Rocks Powerpoint Study Guide

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Igneous Rocks Powerpoint Study Guide
A Rock is:
A group of minerals that have been “put together” in several
different ways.
The Three types of rocks include:
1. igneous
2. sedimentary
3.metamorphic
1. A. Sedimentary rocks are formed by the Deposition, Compaction and
Cementation (Lithification) of Sediments. They are also formed by the
Crystallization or Chemical Reaction of Minerals in Solution in water.
B. Igneous Rocks are formed by the Crystallization, (Cooling and Hardening) of
Magma (molten rock below ground) or Lava (molten rock above ground).
C. Metamorphic rocks are formed by the Recrystallization or Chemical Change of
minerals due to Heat and/or Pressure. Igneous Rocks are identified based upon:
1. 1. Mineral Composition
2. Location of Crystallization
3. Texture of Grain Size
Mineral Composition
A. High Silica rocks are called ____Felsic_______ Igneous Rocks and are
___light__ in color. Felsic Igneous rocks have a Silica content of
approximately _65__%.
B. Low Silica rocks are called ___Mafic______ Igneous Rocks, and are
___dark_______ in color. Mafic Igneous rocks have a Silica content of
approximately _45-50_%.
C. Igneous rocks that have a Silicate composition of 50-65% are considered to be
Intermediate or Andesitic .
Summary:
Essential Question:
Location of Crystallization (Where Igneous rocks are formed)
A. Igneous rocks formed underground from Magma are called Plutonic or
Intrusive rocks.
B. Igneous rocks formed above ground from lava are called “Extrusive” or
“Volcanic” rocks.
Texture or Crystal Size
The faster magma or lava cools, the smaller the size of the crystals in the solidified
material will be..
A. When Magma cools slowly underground, large crystals have time to form.
Therefore, Igneous rocks with large crystals are most likely Plutonic.
B. When Lava cools rapidly above ground, crystals have a limited time to form.
Therefore, Igneous rocks with small or no crystals are most likely Volcanic.
The effect of Silica on the behavior of Magma and Lava.
A. High Silica content causes Felsic Magma to be thick, or viscous, and slowflowing.
B. Low Silica content causes Mafic Magma to be thin or low-viscosity, and fastflowing.
Intrusive Igneous Rock Features
1. Dike: Sheet-like Igneous rock that cuts across the structure of pre-existing rock
2. Sills: Sheet-like Igneous rock that lies parallel to the layering of pre-existing rock
3. Laccoliths: A Laccolith is a vertically developed sill.
4. Batholiths: A Batholith is a large Plutonic mass of Igneous Rock (old Magma
“bubble”).
Summary: