Igneous Rocks and Magma Types

A naturally formed group of minerals bound together.

Igneous rocks are formed from the cooling and crystallization of magma.

Intrusive igneous rocks form deep within the Earth, where the magma cools slowly, resulting in large crystals and a coarse-grained texture.

Extrusive igneous rocks form when magma reaches the surface (lava) and cools quickly, resulting in small crystals and a fine-grained texture.

Felsic magma is rich in silica, making it thick and slow-moving. When it cools, it forms light-colored rocks like granite.

Mafic magma is low in silica, making it thin and fluid. When it cools, it forms dark, dense rocks like basalt.

Intermediate magma has a moderate amount of silica, resulting in a viscosity between felsic and mafic magma. It forms rocks with medium shades of gray and green.

A mix of molten rock, gasses, and mineral crystals.

As magma cools, minerals with the highest melting points crystallize first, followed by minerals with lower melting points in a predictable sequence.

Sheets of magma that intrude into existing rock layers, classified by their orientation: dikes are vertical, sills are horizontal.

Domed masses formed by stiff, non-flowing magma that pushes upward, creating a dome-shaped structure.

The solidified magma that remains after an inactive volcano erodes, forming a central plug.

The largest type of igneous intrusion, forming the core of many mountain ranges, typically made of granite or granodiorite.

A type of igneous intrusion that forms when magma pushes existing rock layers upwards, creating a dome-shaped structure.

The process of cooling magma and solidifying into igneous rock, resulting in distinctive interlocking mineral grains.

Igneous intrusions can contain valuable ore deposits, including platinum, chromium, nickel, and gold.