Dolerite

diabase

 or dolerite

Fine- to medium-grained, dark gray to black intrusive igneous rock. Diabase is one of the dark rocks known commercially as “black granite.” It is extremely hard and tough and is commonly quarried for crushed stone, under the name “trap.” Chemically and mineralogically, diabase closely resembles the volcanic rock basalt, but it is generally somewhat coarser grained.

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Dolerite 

a magmatic rock, effusive or intrusive (near the surface), with a basalt composition. It is characterized by a holocrystalline, coarse-grained doleritic (or ophitic) structure; an aggregate of pyroxene (frequently with olivine) in the form of isometric grains fills out the angular sections between prisms of plagioclase. Dolerite is formed as a result of the slow cooling of molten basalt in the central parts of lava flows or in veins. Dolerite is used in construction as dimension stone and to make crushed stone.