Basic rock
Basic rock
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".[1] 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 texture
Tachylyte, sideromelane, palagonite
Time in Riyadh 
