Igneous rock

Basalt

Mafic, extrusive and fine-grained; brown to dark green to black. Often vesicular or amygdaloidal.

Equivalent: Gabbro is its intrusive equivalent.

**Basalt, thin section.** Wikimedia Commons (author and license on the file page). Source

**Olivine in basalt, thin section.** Wikimedia Commons (author and license on the file page). Source

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More photos and thin sections

Alex Strekeisen: Basalt (thin sections)

Other igneous rocks

Granite · Diorite · Gabbro · Peridotite and dunite · Rhyolite · Andesite · Komatiite · Obsidian, pumice and scoria

Sources

Panchuk, Physical Geology 7.3: Classification of Igneous Rocks