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A dark-gray to black, fine-textured igneous rock composed mainly of feldspar and pyroxene and used for monuments and as crushed stone.
[From French diabase, originally meaning "diorite," (now "basalt or gabbro lightly modified by metamorphism"), coined by French mineralogist Alexandre Brongniart (1770-1847), probably from Greek diabasis, a crossing over (from diabainein, to pass through or over; see diabetes; the rock being so called because it is often found as intrusive sills and dikes in other rocks), or perhaps an alteration of an intended French *dibase (di-, two, from Greek di-; see di-1 + base, basis, from Old French; see base1; the rock being so called in reference to feldspar and amphibole, two important constituent minerals of diorite).]
1. (Geological Science) Brit an altered dolerite
2. (Geological Science) US another name for dolerite
[C19: from French, from Greek diabasis a crossing over, from diabainein to cross over, from dia- + bainein to go]
a fine-grained gabbro occurring as minor intrusions.
[1830–40; < French, =dia- (error for di- two) + base base1]