Extrusive Igneous Rocks

Phonolite is a type of volcanic rock that belongs to the family of igneous rocks. It is characterized by its unique mineral composition and...

Lapilli, which means "little stones" in Italian, refers to small rock fragments ejected during volcanic eruptions. These fragments typically range in size from 2...

Pillow lava is a type of basaltic lava that forms underwater, typically in the ocean. It gets its name from the characteristic pillow-like shapes...

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...

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 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.