dolerite

noun Petrology.

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

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

1. See diabase.