Cumulate rocks are a subtype of this kind of rock. This is the type of rock in which "flow banding" may be observed. Silica content can classify these rocks into felsic, mafic, and ultramafic varieties. Rhyolite, diorite, and gabbro all belong to this group. Varieties of this most abundant type of rock found in the Earth's crust are classified as either intrusive or extrusive depending on whether 
Cumulate rocks are a subtype of this kind of rock. This is the type of rock in which "flow banding" may be observed. Silica content can classify these rocks into felsic, mafic, and ultramafic varieties. Rhyolite, diorite, and gabbro all belong to this group. Varieties of this most abundant type of rock found in the Earth's crust are classified as either intrusive or extrusive depending on whether they were formed below or on the surface. For 10 points, name these rocks that form from cooling magma or lava, contrasted with sedimentary and metamorphic rocks.
Cumulate rocks are a subtype of this kind of rock. This is the type of rock in which "flow banding" may be observed.
igneous rocks