How can you tell igneous and metamorphic rocks apart?

Igneous rock forms from the cooling of magma. This forms a rock that is uniform in composition, and sometimes contains air pocketed texture from the process of cooling. Sedimentary rock is formed of small bits of dirt and stone that bind together after they settle as sediment. This rock is usually distinguishable by the flecks of different types of rock and dirt. Metamorphic rock is any type of rock that is transformed by heat, pressure, or chemical changes. It often becomes denser and smoother than the rock from which it changed.