Extrusive igneous rocks cooled quickly, usually erupting from volcanoes, so they have small or no visible crystals.
(Extrusive igneous rocks; cooled quickly; ) (Extrusive igneous rocks; erupting; from volcanoes; T:usually) (they; have; small or no visible crystals)
Extrusive igneous rocks Extrusive igneous rocks they
cooled quickly erupting have
from volcanoes T:usually
small or no visible crystals