Igneous Rocks
TYPES OF VOLCANIC
ERUPTIONS
EXPLOSIVE
Caused by viscous magma
Spews a lot of smoke and tephra into the air
EFFUSIVE/
NON-EXPLOSIVE
Characterized by very fluid (basaltic) lava
THREE TYPES OF MAGMA
BASALTIC
45-55% Silica(SiO2) content
High in Fe,Mg,Ca
Low in K,Na
High temperatures:1000-1200 C
therefore low viscosity and gas content
ANDESITIC
55-65% Silica content
Intermediate in chemical content
Intermediate temperatures:800-1000 C
therefore medium viscosity and gas content
RHYOLITIC
65-75% Silica content
High in K,Na
Low in Fe,Mg,Ca
Low temperatures:650-800 C
therefore high viscosity and gas content
TWO CLASSIFICATIONS OF MAGMA
MAFIC
Low Silica content
High in Fe,Mg content
"Basic Magma"
FELSIC
High in Silica content
Low Fe,Mg content
"Acidic Magma"
MINERAL TYPES
1.AMPHIBOLE
2.BIOTITE
3.FELDSPAR
4.MUSCOVITE
5.OLIVINE
6.ORTHOCLASE
7.PYROXENE
8.QUARTZ
EXAMPLES OF
IGNEOUS ROCK
GRANITE(3,4)
BASALT(3,7)
ANDESITE(1,2,3,7)
RHYOLITE(2,3,8)
OBSIDIAN(similar to Rhyolite)
TWO TYPES OF IGNEOUS ROCK
EXTRUSIVE/VOLCANIC
Forms from lava cooling and
crystallizing on Earth's surface
INTRUSIVE/PLUTONIC
Forms from magma cooling and
crystallizing in the Earth
TEXTURE OF ROCKS
APHANITIC
Smooth texture from fast cooling
PHANERITIC
Coarse/Rough texture from slow cooling
PORPHYRITIC
Mix of smooth matrix and coarse crystals
from cooling slow to cooling fast
CHARACTERISTICS OF IGNEOUS ROCKS
EXTRUSIVE
Can be either Mafic, Intermediate, or Felsic
MAFIC
Form in ocean basins and hot spots.
Apper dark grey
ex.Basalt
FELSIC
Appear light grey
ex.Granite, Rhyolite
INTRUSIVE
Found in the Earth's mantle
Appear green to black
Low Silica content