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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]
ˌdiaˈbasic adj


(ˈdaɪ əˌbeɪs)

a fine-grained gabbro occurring as minor intrusions.
[1830–40; < French, =dia- (error for di- two) + base base1]
di`a•ba′sic, adj.
References in periodicals archive ?
It runs NE-SW and ENE-WSW upon sandstones along the Botucatu formation in its mid and long courses; in its lowest part it runs over diabasic terrain of basaltic origin between layers of Botucatu (SAAE, 1995).
The only basic alkaline magmatic rocks outcropping in the SCS are lamprophyric and diabasic dykes (Orejana et al.
USP and JP harmonized monographs for Diabasic Calcium Phosphate Anhydrous and Dihydrate, while EP plans to review and sign off on the monographs shortly.