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Etna's Fireworks
Italy's Mount Etna provides a vivid image of one of the birthplaces of igneous rock during a night eruption. Igneous rock forms when magma cools and solidifies. (Lava is magma that has reached the Earth's surface.) Etna also shows off the etymology of igneous, from the Latin word for fire.
Photograph by Carsten Peter

Rocks

See pictures of different rock types (sedimentary, igneous, and others) from National Geographic.