Igneous Rocks

IGNEOUS ROCK

Aa—A rugged form of basalt lava.
Andesite—The typical intermediate arc lava.
Anorthosite—A rare plutonic feldspar-only rock.
Basalt—A bubbly, crystally chunk of this igneous rock from Kilauea.
Diorite—A plutonic rock between granite and gabbro.
Dunite—A plutonic rock made of straight olivine.
Felsite—The volcanic version of granite.
Gabbro—The crystallized, plutonic version of basalt.
Granite—The rock that makes up the bulk of the continents.
Granodiorite—Almost diorite, except that this rock has quartz.
Komatiite—A rare and ancient ultramafic lava.
Lapillistone—A volcanic rock formed of little ash balls.
Latite—A dark lava, the extrusive version of monzonite.
Obsidian—A useful volcanic glass.
Pahoehoe—Smooth-skinned flows of basalt lava.
Pegmatite—The igneous rocks with the biggest crystals.
Peridotite—Dark, dense, rarely seen rock from the Earth's mantle.
Perlite—A lightweight volcanic rock of great usefulness.
Porphyry—An igneous rock with large mineral grains in a fine matrix.
Pumice—A rock made from volcanic eruption products.
Pyroxenite—An uncommon ultramafic rock from the deep sea crust.
Quartz Monzonite—Just like granite, except it's short on quartz.
Rhyolite—The lava type with the highest silica content.
Scoria—A frothy volcanic product much like pumice.
Syenite—A plutonic, alkalic "granite-without-quartz."
Tonalite—A plutonic, felsic "granite-without-alkali feldspar."
Tuff—A rock made from volcanic ash.