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In a widely accepted silica-content classification scheme, rocks with more than 65 percent silica are called felsic; those with between 55 and 65 percent silica are intermediate; those with between 45 and 55 percent silica are mafic; and those with less than 45 percent are ultramafic.
For igneous rock, the composition is divided into four groups: felsic, intermediate, mafic, and ultramafic. These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks.
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. 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.
Felsic and mafic are two terms used to describe the composition of igneous rocks. These terms refer to the relative proportions of light and dark minerals present in the rocks. Felsic rocks are rich in light-colored minerals, while mafic rocks are dominated by dark-colored minerals.
Mafic and felsic rocks represent the extremes of igneous rock compositions, each playing a crucial role in the Earth’s geology. Mafic rocks, with their dark color, higher density, and formation in oceanic settings, contrast with the lighter, less dense felsic rocks that form much of the continental crust.
This classification categorizes igneous rocks into four primary groups: felsic, intermediate, mafic, and ultramafic. Each group has distinct characteristics and typical rock types associated with it.
Felsic and mafic rocks are two main types of igneous rocks, which are rocks that are formed from the cooling and solidification of magma or lava. Felsic rocks are high in silica ( SiO 2 ), while mafic rocks are low in silica.