Mafic

Mafic is an adjective describing a silicate mineral or rock that is rich in magnesium and iron; the term is a portmanteau of the words "magnesium" and "ferric". Most mafic minerals are dark in color and the relative density is greater than 3. Common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, dolerite and gabbro.

In terms of chemistry, mafic rocks are on the other side of the rock spectrum from the felsic rocks. The term roughly corresponds to the older basic rock class.

Mafic lava, before cooling, has a low viscosity, in comparison to felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava, so eruptions of volcanoes made of mafic lavas are less explosively violent than felsic-lava eruptions. Most mafic-lava volcanoes are oceanic volcanoes, like those in Hawaii.

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, sideromelane, palagonite

See also

• QAPF diagram
• List of minerals
• List of rock types

References

ar:معدن قاتم