Igneous rocks form when magma (molten rock) cools and crystallizes, either at volcanoes on the surface of the Earth or while the melted rock is still inside the crust. All magma develops underground, in the lower crust or upper mantle, because of the intense heat there.

Where can find igneous rock?

Where Igneous Rocks Are Found. The deep seafloor (the oceanic crust) is made almost entirely of basaltic rocks, with peridotite underneath in the mantle. Basalts are also erupted above the Earth's great subduction zones, either in volcanic island arcs or along the edges of continents.

What are the most common igneous rocks and where are they generally found?

Basalt and granite are two of the most common igneous rocks found at the earth's surface. They illustrate the diversity of properties igneous rocks have. 5. Forms at the surface, principally in the ocean basins, but also in isolated "hot spots" on the continents.