Common mafic rocks include basalt, diabase and gabbro. Rocks found include andesite, basalt, dacite, diabase, gabbro and rhyolite. That magma crystallizes to mafic rocks such as gabbro and basalt. There are intrusions of igneous rocks, such as gabbro, diabase, and diorite. More mafic rock such as hornblende-biotite gneiss and gabbro are occasionally found. The chemical composition of diorite is intermediate, between that of mafic gabbro and felsic granite. Magnesian orthopyroxene occurs in plutonic rocks such as gabbro (norite) and diorite. There is very little coarser-grained gabbro and diabase. Oceanic crust is composed primarily of basalt and gabbro. There are also incidences of gabbro and diorite, less commonly eclogite. The formation is intruded by plutons of varied composition including gabbro and granite. Pyroxene and feldspar are the major minerals in basalt and gabbro. Rocks like olivine or gabbro can be dug up. Most are sculpted from gabbro, the coarse-grained equivalent of basalt. Boreray is formed of a breccia of gabbro and dolerites.