fraction of dark mafic minerals) is between 50 and 90. Most mafic volcanic rocks are more precisely classified as basalts.

Chemically, mafic rocks are sometimes defined as rocks with a silica content between 45 and 55 wt%, corresponding to the silica content of basalt in the TAS classification. Such rocks are enriched in iron, magnesium, and calcium and typically dark in color. In contrast, the felsic