Extrusive (volcanic) igneous rocks cool and crystallize rapidly on the earth's surface and so have fine grains. Extrusive rocks frequently contain some larger, well-shaped, crystals surrounding by the fine-grained material.

Which rocks contain grains?

Sedimentary rocks are rocks made of lithified sediment. Sediments are grains of rocks, minerals, or mineraloids deposited on the surface of the earth. Reflect on the rock cycle for an indication of the relationships between the rocks that erode to become sediments and sedimentary rocks.

What does extrusive rock contain?

Extrusive rock, any rock derived from magma (molten silicate material) that was poured out or ejected at Earth's surface.