Igneous rock

Andesite

Intermediate, extrusive and fine-grained, often grey.

Equivalent: Diorite is its intrusive equivalent.

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

**Porphyritic andesite, Nevada.** Wikimedia Commons (author and license on the file page). Source

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More photos and thin sections

Alex Strekeisen: Andesite (thin sections)

Other igneous rocks

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

Sources

Panchuk, Physical Geology 7.3: Classification of Igneous Rocks