Chapter RocksIgneous Rocks

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Origin of Igneous Rocks

• Igneous comes from the Latin word for fire – ignis• Igneous rocks are formed by lava being ejected by

volcanoes. When the lava cools it becomes an igneous rock. Depending on the mineral composition of the lava, is what makes the different type of igneous rock.

INTRUSIVE ROCK

EXTRUSIVE ROCK

Intrusive Rocks

• Intrusive rocks usually have larger grained texture to them because they have a much longer time to cool which allows the minerals to form into bigger clumps in the rock.

Extrusive Rocks

• Extrusive rocks on the other hand are able to cool much, much quicker which doesn’t allow the minerals in the rock to Extrusive rocks then have a finer grained texture than intrusive rocks.

• clump together too much.

Classification of Igneous Rocks

• Basaltic Rock: The type of magma that forms these rocks is rich in iron and magnesium. These rocks are usually dense, heavy, dark-colored rocks.– EX: Gabbro, Basalt, Scoria

Classification of Igneous Rocks

• Granitic and Andesitic Rock: The type of magma that forms these type of rocks is thick and stiff and has a lot of silica. Usually this magma can buildup a lot of gas and pressure– EX: Diorite, Granite, Pumice, and Obsidian

obsidian

gabbro

basaltpumicegraniterhyolite

Pophyriticandesite

Volcanic stuff

Andesite

peridotitescoriadiorite