Mafic

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Mafic

Mafic is an adjective describing a silicate mineral or rock that is rich in magnesium and iron; the term was derived by contracting "magnesium" and "ferric". Most mafic minerals are dark in color and the specific gravity

Specific gravity

Specific gravity is defined as the ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure, typically at 4?C and , making it a dimensionless quantity ....
is greater than 3. Common rock-forming mafic minerals include olivine

Olivine

The mineral olivine is a magnesium iron Silicate minerals with the formula 2siliconoxygen4. It is one of the most common minerals on Earth, and has also been identified in meteorites and on the Moon, Mars, and comet Wild 2....
, pyroxene

Pyroxene

The pyroxenes are a group of important rock-forming silicate minerals found in many igneous and metamorphic rock rock . They share a common structure comprised of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems....
, amphibole

Amphibole

Amphibole defines an important group of generally dark-colored rock-forming Silicate minerals minerals, composed of double chain SiO4 tetrahedron, linked at the vertices and generally containing ions of iron and/or magnesium in their structures....
, and biotite

Biotite

Biotite is a common Silicate minerals#Phyllosilicates mineral within the mica group, with the approximate chemical formula K3AlSi3O102....
. Common mafic rocks include basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
and gabbro

Gabbro

Gabbro refers to a large group of dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. The rocks are Intrusive, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
.

In terms of chemistry, mafic rocks are on the other side of the rock spectrum from the felsic

Felsic

Felsic is a term used in geology to refer to silicate minerals, magma, and rock which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium....
rocks.

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Encyclopedia

Specific gravity

Olivine

Pyroxene

Amphibole

Biotite

Biotite is a common Silicate minerals#Phyllosilicates mineral within the mica group, with the approximate chemical formula K3AlSi3O102....
. Common mafic rocks include basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
and gabbro

Gabbro

Felsic

Lava

Lava is molten Rock expelled by a volcano during an eruption. When first expelled from a volcanic vent, it is a liquid at temperatures from 700 ?C to 1,200 ?C ....
, before cooling, has a low viscosity

Viscosity

Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness"....
, in comparison to felsic

Felsic

Felsic is a term used in geology to refer to silicate minerals, magma, and rock which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium....
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 Hawaii

Hawaii

File:Pahoehoe and Aa flows at Hawaii.jpgThe State of Hawaii is a U.S. state in the United States, located on an archipelago in the central Pacific Ocean southwest of the continental United States, southeast of Japan, and northeast of Australia....
.

Rock Texture	Name of Mafic Rock
Pegmatitic Pegmatite Pegmatite is a very coarse-grained igneous rock that has a grain size of 20 mm or more; such rocks are referred to as pegmatitic.Most pegmatites are composed of quartz, feldspar and mica; in essence a "granite"....	Gabbro Gabbro Gabbro refers to a large group of dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. The rocks are Intrusive, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass.... pegmatite Pegmatite Pegmatite is a very coarse-grained igneous rock that has a grain size of 20 mm or more; such rocks are referred to as pegmatitic.Most pegmatites are composed of quartz, feldspar and mica; in essence a "granite"....
Coarse grained (phaneritic Phaneritic Phaneritic is a term usually used to refer to igneous rocks Particle size. It means that the size of grains in the Rock are large enough to be distinguished with the unaided eye as opposed to aphanitic .... )	Gabbro Gabbro Gabbro refers to a large group of dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. The rocks are Intrusive, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
Coarse grained and porphyritic	Porphyritic gabbro Gabbro Gabbro refers to a large group of dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. The rocks are Intrusive, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
Fine grained (aphanitic)	Basalt Basalt Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
Fine grained and porphyritic	Porphyritic basalt Basalt Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
Pyroclastic	Basalt Basalt Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet.... tuff Tuff Tuff is a type of Rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. Tuff is also sometimes called tufa, particularly when used as construction material.... or breccia Breccia Breccia is a rock composed of angular fragments of several minerals or rocks in a Matrix , that is a Cementation material, that may be similar or different in composition to the fragments....
Vesicular Vesicular texture Vesicular texture is a volcanic Rock texture characterised by, or containing, many vesicles. The texture is often found in extrusive aphanite, or glassy, igneous rock....	Vesicular basalt Basalt Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
Amygdaloidal	Amygdaloidal basalt Basalt Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
Many small vesicles	Scoria Scoria Scoria is a textural term for Vesicular texturevolcanic rock. It is commonly, but not exclusively, basaltic or andesite in composition. Scoria is light as a result of numerous macroscopic ellipsoidal vesicles, but most scoria has a specific gravity greater than 1, and sinks in water....
Glassy	Tachylyte Tachylyte Tachylite is a vitreous form of basaltic volcanic glass. This "glass" is formed naturally by the rapid cooling of molten basalt. It is a basic type of igneous rock that is decomposable by acids and readily fusible.... , sideromelane Sideromelane Sideromelane is a vitreous basaltic volcanic glass, usually occurring in palagonite tuff, for which it is characteristic. It is a less common form of tachylite, with which it usually occurs together; however it lacks the iron oxide crystals dispersed in the glass, and therefore appearing transparent and pure, with yellow-brown color, instead... , palagonite Palagonite Palagonite is an alteration product from the interaction of water with volcanic glass of chemical composition similar to basalt. Palagonite can also result from the interaction between water and basalt melt....

Mafic

See also