GEOL V02L Igneous Rocks

Basalt

VOLCANIC. Setting: Oceanic crust, divergent boundaries. Composition: mafic. Minerals: pyroxene, plagioclase.

Andesite

VOLCANIC. Setting: subduction zone, volcanic arcs. Composition: intermediate. Minerals: plagioclase, amphibole.

Rhyolite

VOLCANIC. Setting: continental arcs or rifts. Composition: felsic. Minerals: quartz, K-feldspar

Granite

PLUTONIC. Setting: continental crust, plutons. Composition: felsic. Minerals: quartz, feldspar, mica.

Diorite

PLUTONIC. Setting: continental arcs, plutons. Composition: intermediate. Minerals: plagioclase, amphibole.

Gabbro

PLUTONIC. Setting: oceanic crust, plutons. Composition: mafic. Minerals: pyroxene, plagioclase.

Peridotite

PLUTONIC. Setting: mantle. Composition: ultramafic. Minerals: olivine, pyroxene.

Pumice

VOLCANIC. Setting: explosive eruptions. Composition: felsic. Minerals: quartz, feldspar fragments.

Scoria

VOLCANIC. Setting: explosive eruptions. Composition: mafic. Minerals: pyroxene, plagioclase fragments.

Obsidian

VOLCANIC. Setting: rapid lava cooling. Composition: felsic. Minerals: silica.