Geol. of or pertaining to igneous rocks that are rich in dark-colored minerals and that contain magnesium and iron and a comparatively low level of silica
Origin:
ma(gnesium) + L f(errum), iron + -ic
See mafic in American Heritage Dictionary 4
adjective
Containing or relating to a group of dark-colored minerals, composed chiefly of magnesium and iron, that occur in igneous rocks.