What term describes igneous rocks that crystallize below the surface?

• A. Intrusive igneous rocks
• B. Extrusive igneous rocks
• C. Sedimentary rocks
• D. Metamorphic rocks

Answer: (A)

Crystallization location shapes the rock’s texture and name. When magma cools underground, it does so slowly, giving crystals time to grow large. Rocks that form this way are intrusive igneous rocks, and they typically have coarse grains you can see with the naked eye—granite is a common example.

If cooling happens at or near the surface, the rocks crystallize quickly, producing very small crystals or a glassy texture; these are extrusive igneous rocks. The other two rock groups aren’t igneous at all—sedimentary rocks come from cemented sediment, and metamorphic rocks come from existing rocks altered by heat and pressure.

So, the term for igneous rocks that crystallize below the surface is intrusive igneous rocks.