Mafic is a term used in geology for silicate minerals, magmas, volcanic, and intrusive igneous rocks that have relatively high concentrations of the heavier elements. The term is a combination of " magnesium" and ferric, the Latin word for iron(III), but mafic magmas also are rich in calcium and sodium. Mafic minerals are usually dark in color and have specific gravities greater than 3. Common rock-forming mafic minerals include olivine, pyroxene, amphiboleHornblende) Amphibole defines an important group of dark-colored rock-forming silicate minerals composed of double chain SiO tetrahedra linked at the vertices and generally containing ions of iron and/ or magnesium in their structures. In chemical composi, biotiteBiotite is a common silicate mineral that contains potassium, magnesium, iron and aluminium. It is sometimes called "iron mica" and is found in granitic rocks, gneisses, and schists. Like other mica minerals, biotite has a highly perfect basal cleavage, i and other micaThe mica group of minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic with a tendency towards pseudo-hexagonal crystals and are similar in chemical composition. The highly perfect cleavage, which iss, augiteAugite is a mafic mineral described chemically as (Ca, Na)(Mg, Fe, Al)(Al, Si)O or calcium sodium magnesium iron aluminium silicate. Structurally, it is a solid solution of the pyroxene group which also contains diopside and hedenbergite. The crystals are and the calcium-rich plagioclase feldsparsFeldspar (from the German Feld field, and Spat a rock that does not contain ore) is the name of an important group of rock-forming minerals which make up perhaps as much as 60% of the Earth's crust. They crystallize from magma in both intrusive and extrus. Common mafic rocks include basaltBasalt is an extrusive igneous rock, sometimes porphyritic, and is often both fine-grained and dense. Basalt in the tops of subaerial lava flows and cinders will often be highly vesiculated, imparting a lightweight "frothy" texture to the rock. The term b and gabbroGabbro is a dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. It is a plutonic rock, formed when molten magma is trapped beneath the Earth's surface and cools slowly into a hard, coarsely crystalline mass. It is dense, greenish.
In terms of chemistry, mafic rocks are on the other side of the rock spectrum from the so-called felsic rocks. The term roughly corresponds to the older basic rock class.
