Diabase is a type of igneous rock that forms from the cooling and solidification of magma beneath the Earth's surface. It is primarily composed of plagioclase feldspar and pyroxene, giving it a dark color and a fine-grained texture. Diabase is often found in dike formations, which are vertical or near-vertical sheets of rock that cut through other rock layers. This rock is commonly used in construction and as an aggregate in concrete due to its durability and strength. Diabase can also be found in various geological settings, including areas associated with volcanic activity and mid-ocean ridges.