Mafic

Mafic is a term used in geology for silicate minerals, magmas, and rocks which have relatively high concentrations of the heavier elements. The term is a combination of "magnesium" and "ferric," the Latin word for iron, but mafic magmas also are rich in calcium and sodium.

Mafic minerals are usually dark in color and have specific gravities greater than 3. Common rock-forming mafic minerals include olivine, pyroxene, amphibole, biotite and other micas, augite and the plagioclase feldspars. Common mafic rocks include basalt and gabbro.

In terms of chemistry, mafic rocks are on the other side of the rock spectrum from the so-called felsic rocks.

Rock Texture	Name of Mafic Rock
Pegmatitic	Gabbro pegmatite
Coarse grained (phaneritic)	Gabbro
Coarse grained and porphyritic	Porphyritic gabbro
Fine grained (aphanitic)	Basalt
Fine grained and porphyritic	Porphyritic basalt
Pyroclastic	Basalt tuff or breccia
Vesicular	Vesicular basalt
Amygdaloidal	Amygdaloidal basalt
Many small vesicles	Scoria
Glassy	Tachylyte or palagonite