Igneous Rocks - Vocabulary Flashcards

Vocabulary flashcards covering key igneous rock concepts: formation, classification, textures, composition, minerals, and examples.

Igneous Rock

A rock formed from the cooling and solidification of molten rock (magma beneath the surface or lava at the surface).

Magma

Molten rock located beneath Earth's surface.

Lava

Molten rock that erupts onto the surface and then cools to form extrusive rocks.

Intrusive

Igneous rocks that form when magma cools and solidifies beneath Earth's surface, usually coarse-grained.

Extrusive

Igneous rocks that form when lava erupts and cools on Earth's surface, usually fine-grained.

Texture

The feel or appearance of a rock; in igneous rocks, relates to crystal size and arrangement.

Coarse Texture

Large crystals formed by slow cooling underground (intrusive rocks).

Fine Texture

Small crystals formed by rapid cooling at the surface (extrusive rocks).

Crystal Size

Size of the crystals in a rock, determined by the cooling rate.

Origin

Classification criterion for igneous rocks based on where they form (intrusive vs extrusive).

Composition

Mineral makeup of a rock (e.g., quartz, feldspar, mica, amphibole; metals).

Quartz

A common mineral in igneous rocks; a hard silicate (SiO2).

Feldspar

Group of common minerals in igneous rocks (plagioclase, orthoclase).

Mica

Sheet silicate mineral (e.g., muscovite, biotite) in igneous rocks.

Amphibole

Mineral group (hornblende) found in many igneous rocks.

Granite

Intrusive, coarse-grained igneous rock; used for countertops and historically in architecture.

Basalt

Mafic extrusive igneous rock; crushed basalt is commonly used in construction.

Pumice

Lightweight, porous extrusive rock used as a cleaning material.

Magma Chamber

Underground pocket where magma collects before solidifying.

Molten

Liquefied by extreme heat.

Cooling Rate

Speed at which molten rock solidifies; slow cooling yields large crystals, fast cooling yields small crystals.

Rock Cycle (Igneous Focus)

Igneous rocks form from cooling of molten rock (magma below ground or lava above ground).