Extrusive Igneous Rocks

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Extrusive igneous rocks, additionally referred to as volcanic rocks, are fashioned on the crust’s surface due to the partial melting of rocks within the mantle and crust. Extrusive Igneous Rocks are listed below.

Volcanic Bomb

Volcanic bomb is pyroclastic rock that is a cooling of a mass of lava it flies thorough the air after eruption. If it is...


Scoria is a type of volcanic rock that forms from the solidification of molten lava. It is commonly found around and on the surface...


Pumice is a volcanic rock that consists of highly vesicular rough textural rock glass. It generally light colored. It is created when gas-saturated liquid...
Camptonite lamprophyre (Mesozoic, 100-200 Ma; Campton Falls, Grafton County


Lamprophyre is ultrapotassic igneous rock that is occurring as dikes, lopoliths, loccoliths, stocks and small intrussion. It is alkaline silica-undersaturated mafic or ultramafic rocks...
Pyroxenite (Stillwater Complex, Neoarchean)


Pyroxenite is an ultramafic igneous rock that contain pyroxene group minerals such as augite, diopside, hypersthene, bronzite or enstatite. This is a coarse-grained rock...


Obsidian is an igneous rock that forms when molten rock material cools so rapidly that atoms are unable to arrange themselves into a crystalline structure. It is an amorphous material known as a "mineraloid." The result is a volcanic glass with a smooth uniform texture that breaks with a conchoidal fracture .


Basalt is the most common rock on Earth’s surface. Specimens are black in color and weather to dark green or brown. Basalt is rich in iron and magnesium and is mainly composed of olivine, pyroxene, and plagioclase. Most specimens are compact, fine-grained, and glassy. They can also be porphyritic, with phenocrysts of olivine, augite, or plagioclase. Holes left by gas bubbles can give basalt a coarsely porous texture.