Diabase is a mafic, holocrystalline, igneous rock equivalent to volcanic basalt or plutonic gabbro. Diabase is also called dolerite in many references outside North America. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine grained to aphanitic chilled margins which may contain tachylite (dark mafic glass). Diabase normally has a fine, but visible texture of euhedral lath shaped plagioclase crystals (62%) set in a finer matrix of clinopyroxene, typically augit… (More on Diabase)