Understanding Igneous Rocks

What is the primary basis for classifying igneous rocks?

• Their color

• Their chemical composition

• Their location of formation

• Their age

Which minerals are typically found in mafic rocks?

• Olivine and pyroxene

• Quartz and feldspar

• Mica and biotite

• Calcite and dolomite

What distinguishes felsic rocks from mafic rocks?

• Felsic rocks are denser

• Felsic rocks are darker

• Felsic rocks are lighter and less dense

• Felsic rocks contain more iron

What are ultramafic rocks primarily composed of?

• High amounts of iron and magnesium

• High amounts of silica

• High amounts of aluminum

• High amounts of calcium

What are xenoliths?

• Pieces of the upper mantle embedded in lava

• Crystals formed in cooling magma

• Volcanic ash deposits

• Sedimentary rock fragments

What type of rock is formed from the partial melting of basalt?

• Andesite

• Diorite

• Granite

• Rhyolite

What is the primary difference between andesite and diorite?

• Andesite is volcanic, diorite is plutonic

• Andesite is lighter in color

• Diorite is formed from felsic magma

• Diorite contains more quartz

What is Bowen's Reaction Series?

• A process of volcanic eruption

• A sequence of mineral crystallization in cooling magma

• A method to classify sedimentary rocks

• A type of igneous rock

Which mineral crystallizes first in Bowen's Reaction Series?

• Feldspar

• Olivine

• Quartz

• Biotite

What happens to the minerals as they crystallize in Bowen's Reaction Series?

• They dissolve back into the magma

• They settle at the bottom

• They float to the top

• They remain suspended in the magma