Mafic

mafic 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 olivinepyroxeneamphibole, and biotite. Common mafic rocks include basaltdiabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian.

Basalt

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

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 textureTachylytesideromelanepalagonite

 


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 Metasyntactic variable, which is released under the 
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