igneous
adj.adj. describing rock that was formed when hot, melted rock (magma) cooled and hardened. You use this to talk about rocks like granite or basalt.
adj. relating to or denoting rock formed by the cooling and solidification of molten magma or lava. Often used to distinguish these rocks from sedimentary or metamorphic types.
Granite is a common type of igneous rock.
The geologist identified the sample as an igneous rock because it had a rough, crystalline texture formed by slow cooling.
Igneous formations often provide a chronological record of a region's volcanic history, as the chemical composition of the magma can indicate the depth and pressure of its origin.
From Latin igneus (“fiery”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Last updated May 25, 2026