what type of rock makes up the oceanic crust

Most of the oceanic crust is made of the igneous rock basalt , with deeper parts made largely of gabbro; overall it is described as mafic rock rich in iron and magnesium.

Quick Scoop

• The upper oceanic crust is mainly fine‑grained, dark volcanic basalt that forms when lava cools quickly on the seafloor.

• Beneath that, the lower oceanic crust is mostly coarse‑grained gabbro that crystallizes more slowly at depth.

• Because these rocks are mafic (rich in magnesium and iron), oceanic crust is denser than continental crust.

So if you need one simple answer to “what type of rock makes up the oceanic crust,” the go‑to word is basalt (with gabbro underneath). Information gathered from public forums or data available on the internet and portrayed here.