Chapter 6, Section 1Igneous Rocks

• Igneous Rock • A rock that forms from the cooling and hardening of molten rock

• Magma

• Lava

• Molten rock found under the Earth’s Surface

• Molten Rock found on the Earth’s surface

• Felsic magma

• Mafic magma

• Light in color, very thick; has a high silica content

• Dark in color and very thin; low silica content

• Intrusive igneous rocks

• Rocks that form underground from magma

• Take a long time to cool because underground (holds the heat in)

• Extrusive igneous rock

• Forms on the Earth’s surface from lava

• Cools and hardens very quickly b/c on the Earth’s surface

• Crystal size

• Porphyry

• Intrusive igneous rocks tend to have LARGE crystals

• The longer it takes the rock to cool, the larger the crystals will be

• VERY large crystals

• Granite family • Felsic magmas• Granite• Rhyolite• Pumice• Obsidian

• Gabbro family • Mafic magmas• Gabbro• Basalt• Scoria• Diabase

• Diorite family • Intermediate magma

• Diorite and andesite