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"Igneous" refers to rocks of volcanic origin. "Extrusion" refers to the process of a material being forced through a cavity of another material. (Think "Play-Doh Fun Factory." :) ) So, extruded igneous rocks are formed when liquid magma (volcanic rock) is forced through an opening (like a volcanic vent) and then cools and hardens into volcanic rock.

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Zane Blick

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2y ago
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12y ago

Extrusive igneous rock is one of two different types of igneous rocks. The other kind is intrusive igneous rock. Intrusive igneous rock is formed when magma in Earth's lithosphere cools and hardens. Extrusive igneous rock is formed when lava on Earth's surface cools and hardens.

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14y ago

Extrusive igneous rock is formed from the solidification of lava on or above the surface. Rapid cooling from exposure to air or water results in rapid crystallization of their component minerals, normally creating a fine grained texture as opposed to intrusive igneous rock which has a coarser texture.

Examples of extrusive igneous rock would include obsidian, pumice, basalt, and rhyolite.

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12y ago

Any ingenious rock derived from magma that is poured out or ejected at the Earth's surface. Extrusive rocks are usually distinguished from intrusive rock on the basis of their texture and mineral composition. Lava flows and pyroclastic debris (fragmented volcanic material) are extrusive; they are commonly glassy (e.g., obsidian) or finely crystalline (e.g., basalts and felsites).

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12y ago

This refer to igneous rocks which form above the earth surface due to lava flow.the rocks are normally fine grained due to rapid cooling attributed to low pressure and temperature conditions on the earth surface.

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Wiki User

9y ago

Extrusive rocks are rocks that are derived from magma. These rocks were either poured out or ejected at the Earth's surface.

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14y ago

this forms when lava cools on earths surface

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14y ago

extrusive rocks can form from Basaltic Lava and Andesitic Lava. :)

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Wiki User

11y ago

By magma cooling it's formed on the surface of earth by volcano activity

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Wiki User

7y ago

Molten lava (from a volcano)

Salt (from a salt dome)

Mud (from a mud volcano)

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Q: From what material does a extrusive rock form?
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