The word igneous comes from the Latin for fire ‘ignis’. This gives us a clue as to their formation because they are the result of massive volcanic activity millions of years ago. Basalt is ...

Igneous rocks close igneous rockIgneous rocks ... If magma erupts on the surface as lava, it will form extrusive rock, e.g. basalt. These rocks are formed when magma solidifies.

producing extrusive or volcanic igneous rocks like basalt. As magma cools, the minerals within it begin to crystallize and interlock to create solid rock. The rate of cooling affects the size of ...