lamprophyre

noun Petrology.

1. any dark intrusive rock in which dark minerals occur both as phenocrysts and as groundmass.

noun

1. any of a group of basic igneous rocks consisting of feldspathoids and ferromagnesian minerals, esp biotite: occurring as dykes and minor intrusions

1. A dark igneous rock, having a porphyritic texture in which both the phenocrysts (larger crystals) and the matrix consist primarily of pyroxene, hornblende, and biotite.