dolerite

UK: /ˈdɒləˌraɪt/ US: (dol′ə rīt′)

WordReference Random House Unabridged Dictionary of American English © 2026

dol•er•ite  (dol′ə rīt′), n. [Petrol.]

1. Rocks a coarse-grained variety of basalt.
2. Rocks any of various other igneous rocks, as diabase.
3. Rocks any basaltlike igneous rock whose composition can be determined only by microscopic examination.

• Greek doler(ós) deceitful (derivative of dólos wile) + French -ite -ite¹
• French dolérite
• 1830–40;

dol•er•it•ic  (dol′ə rit′ik), adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

dolerite / ˈdɒləˌraɪt/ noun

1. a dark basic intrusive igneous rock consisting of plagioclase feldspar and a pyroxene, such as augite; often emplaced in dykes
2. any dark igneous rock whose composition cannot be determined with the naked eye

Etymology: 19th Century: from French dolérite, from Greek doleros deceitful; so called because of the difficulty of determining its composition

doleritic / ˌdɒləˈrɪtɪk/ adjective