Definition of dolerite in US English:



  • A dark, medium-grained igneous rock, typically with ophitic texture, containing plagioclase, pyroxene, and olivine. It typically occurs in dikes and sills.

    Also called diabase
    • ‘We reached Fault Bluff, a dark angular mountain with faulted dolerite rock, around 10: 00 P.M. that night.’
    • ‘Many tales have been told about the impressive arch that was named in 1823 by the crew of the British survey ship, the Barracouta, because of the portal carved through an island rock castle with sheer dolerite walls.’
    • ‘These supracrustal rocks are intruded by dolerite dykes that have been deformed and metamorphosed together with the country rock.’
    • ‘Dark dolerite mountains of the Warren Range had a light snow cover that accentuated the flow banding in the rock.’
    • ‘Neither had iron tools and instead used such hard stones as flint, jade, dolerite, basalt, and serpentine to make axes, knives, and chisels.’


Mid 19th century: from French dolérite, from Greek doleros ‘deceptive’ (because it is difficult to distinguish from diorite).