Pegmatites are igneous intrusive rocks containing extremely coarse-grained crystals.
(Pegmatites; are; igneous intrusive rocks containing extremely coarse-grained crystals) (igneous intrusive rocks; containing; extremely coarse-grained crystals)
Pegmatites igneous intrusive rocks
are containing
igneous intrusive rocks containing extremely coarse-grained crystals
extremely coarse-grained crystals