X1011780410-00130-37577</DOCNO> Cronin's Supplemental Notes on Ignous Rocks This page's URL is http://www.uwm.edu/~vcronin/422-100.igrox.snotes.html It was last revised February 9, 2000 Igneous Rocks Look for some hints for identifying the igneous specimens in the lab at www.uwm.edu/~vcronin/422-100.igrox.props.html Igneous Rocks (from the Latin ignis -- fire) Introductory notes Types of igneous rocks Intrusive : solidifies below Earth's surface (e.g., granite) Extrusive : solidifies on Earth's surface (e.g., basalt) Terms Magma : generic term for molten rock Lava : generic term for extrusive igneous rock Magma: Molten Rock Magma is a complex mixture of liquid, solid & gas Liquid Solid, composed of early-formed crystals Gas/volatiles Can be up to 14% of magma volume Mostly comprised of carbon dioxide (CO 2 ) and water (H 2 O) vapor Influences the viscosity & melting point: high volatile content increases viscosity & explosiveness of eruptions Magma types Mafic magma Characteristics: less than or equal to 50% silica;
(Molten Rock Magma; is; a complex mixture of liquid) (liquid; composed; of early-formed crystals) (Molten Rock Magma; Influences; the viscosity & melting point) (Gas/volatiles; Can be; up to 14% of magma volume) (magma volume; Mostly comprised; of carbon dioxide (CO 2 ) and water)
Molten Rock Magma liquid Molten Rock Magma Gas/volatiles magma volume
is composed Influences Can be Mostly comprised
a complex mixture of liquid
of early-formed crystals
the viscosity & melting point
up to 14% of magma volume
of carbon dioxide (CO 2 ) and water