Igneous rocks are classified by their texture and mineral composition - as to whether they are intrusive (larger crystals) or extrusive (very small crystals), and the identifiable minerals.
(Igneous rocks; are classified; by their texture and mineral composition; as to whether they are intrusive (larger crystals) or extrusive (very small crystals), and the identifiable minerals) (they; are; intrusive)
Igneous rocks they
are classified are
by their texture and mineral composition as to whether they are intrusive (larger crystals) or extrusive (very small crystals), and the identifiable minerals
intrusive