A rock formed when magma cools and solidifies is called what?

• A. Igneous.
• B. Sedimentary.
• C. Metamorphic.
• D. Metallic.

Answer: (A)

When molten rock from beneath the surface (magma) cools and hardens, it becomes an igneous rock. This formation path—cooling and solidifying of molten material—defines igneous rocks, whether they crystallize underground as coarse-grained granite or erupt at the surface as fine-grained basalt or glassy obsidian. In contrast, sedimentary rocks form from weathered fragments that are deposited and cemented together, and metamorphic rocks form when existing rocks are altered by heat and pressure. Metallic isn’t a rock type, since it describes composition, not how the rock formed. So the rock formed by magma cooling and solidifying is igneous.