Mafic

Basalt

Mafic is a term used in geology to describe silicate minerals, magmas, and igneous rocks that are rich in magnesium and iron, while being relatively low in silica content. Common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian.

Mafic rocks and minerals occupy one end of a spectrum of chemical composition, with felsic rocks and minerals at the opposite end. In general, mafic rocks tend to be dark in color, dense, and found primarily in oceanic crust, while felsic rocks tend to be light in color, less dense, and found primarily in continental crust.