gabbro
A dark, visibly grained intrusive igneous facade stone formed underground, here also including finer-grained diabase.
Gabbro is a hard igneous rock similar to basalt except that it is composed of visibly distinct crystalline grains (whereas basalt is basically homogeneously dark gray without visible grains). It is formed when magma cools and hardens under the Earth's surface (basalt is produced by lava cooling at the surface).
Gabbro is usually dark in color, and can have a natural greenish, reddish, or bluish tint. It includes the rock type diabase, which is finer grained than gabbro.
The visible crystalline texture distinguishes it from generally fine-grained basalt. This material entry also includes diabase as stated above, even though its grains are finer.