More on Igneous Rocks

An introduction to the first great class of rock types.

Info on and photos of the major igneous rock types.

The major texture types found in igneous rocks.

Diagrams showing IUGS classification of phaneritic igneous rocks (QAP ternary diagrams) and aphanitic igneous rocks (TAS graph).

Readers share their favorite igneous rocks.

Pictures of erupted, or extrusive, igneous rocks.

Basalt has a key role in Earth's tectonic cycle.

Basalt in pictures from land and sea.

An article about the unique carbonate lava of Oldoinyo Lengai, Tanzania's (and the world's) weirdest volcano.

Granite is the signature rock of the continents.

How geologists sort out granite from the rocks that look like it.

Pictures of various granites and granitic rocks.

Obsidian is an extreme variety of igneous rock with a glassy texture.

See peridotite in the hand and in the landscape.

Phenocrysts are distinctly large crystals in an igneous rock. Here are pictures of some of the minerals that form phenocrysts.

Pillow lavas from contemporary to Ordovician.

One of the Web's geo-geek treasures, Robert Reed's site has been "out there" since 1995 with fanciful and solid material about granite.

Karl-Peter Kelber's Links for Mineralogists site has a big grab-bag of rock-related sites for all levels of users.