Mafic

A mafic (portmanteau of "magnesium" and "ferric") mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron.[1] Most mafic minerals are dark in color, and 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.[2]

Chemically, mafic rocks are enriched in iron, magnesium and calcium and typically dark in color. In contrast, the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium. The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older basic rock class.[3]

Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava. As a result, eruptions of volcanoes made of mafic lavas are less explosively violent than felsic-lava eruptions.[4]

Volcanic rocks: Subvolcanic rocks: Plutonic rocks:

Picrite basalt Peridotite

Basalt Diabase (Dolerite) Gabbro

Andesite Microdiorite Diorite

Dacite Microgranodiorite Granodiorite

Rhyolite Microgranite Granite