Mafic

Basalt

Mafic is an adjective describing a silicate mineral or igneous rock that is rich in magnesium and iron, and is thus a portmanteau of magnesium and ferric.[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.

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.

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. Most mafic-lava volcanoes are shield volcanoes,[citation needed] like those in Hawaii.

Rock textureName of mafic rock
PegmatiticGabbro pegmatite
Coarse grained (phaneritic)Gabbro
Coarse grained and porphyriticPorphyritic gabbro
Medium grainedDiabase or Dolerite, Microgabbro
Fine grained (aphanitic)Basalt
Fine grained and porphyriticPorphyritic basalt
PyroclasticBasalt tuff or breccia
VesicularVesicular basalt
AmygdaloidalAmygdaloidal basalt
Many small vesiclesScoria
Glassy textureTachylyte, sideromelane, palagonite
Other Languages
Afrikaans: Mafies
العربية: صخر مافي
български: Мафичен
català: Màfic
čeština: Mafity
español: Máfico
euskara: Mafiko
فارسی: مافیک
français: Mafique
Bahasa Indonesia: Mafik
íslenska: Basísk kvika
italiano: Femico
עברית: מאפי
Nederlands: Mafisch
日本語: 苦鉄質
norsk nynorsk: Mafiske mineral
português: Máfico
Simple English: Mafic
slovenčina: Mafický
slovenščina: Mafičnost
suomi: Mafinen
Türkçe: Mafik
Tiếng Việt: Mafic
中文: 铁镁质