Which rock type forms when hot molten material cools?

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

Answer: (A)

Igneous rocks come from the cooling and solidification of molten material. When magma beneath the surface or lava at the surface loses heat, it crystallizes to form these rocks. The rate of cooling influences texture: slow cooling produces coarse crystals (intrusive), while rapid cooling yields fine crystals or volcanic glass (extrusive). Sedimentary rocks form from weathering, transport, deposition, and lithification of sediments. Metamorphic rocks form when existing rocks are altered by heat and pressure. Clastic describes a texture of sedimentary rocks made from rock fragments. So, the rock type formed from cooling molten material is igneous.