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QAPF diagram for classification of plutonic rocks. A QAPF diagram is a doubled-triangle plot diagram used to classify intrusive igneous rocks based on their mineralogy.The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)", which are the four mineral groups used for classification in a QAPF diagram.
The atomic scale structure of olivine looking along the a axis. Oxygen is shown in red, silicon in pink, and magnesium/iron in blue. A projection of the unit cell is shown by the black rectangle. The molecular structure of peridot consists of isomorphic olivine, silicate, magnesium and iron in an orthorhombic crystal system.
Dunite may also form by the accumulation of olivine crystals on the floor of large basaltic or picritic magma chambers. These " cumulate " dunites typically occur in thick layers in layered intrusions , associated with cumulate layers of wehrlite , olivine pyroxenite , harzburgite , and even chromitite (a cumulate rock consisting largely of ...
Kimberlite: formed in volcanic pipes and at least 35% olivine [9] Kimberlite is a highly brecciated variant of peridotite formed in volcanic pipes and is known for being the host rock to diamonds. Unlike other forms of peridotite, kimberlite is quite rare. [10] Pyroxene peridotite: From 40% to 90% olivine and less than 5% hornblende
Basalt. 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.
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Ringwoodite is polymorphous with forsterite, Mg 2 SiO 4, and has a spinel structure.Spinel group minerals crystallize in the isometric system with an octahedral habit. Olivine is most abundant in the upper mantle, above about 410 km (250 mi); the olivine polymorphs wadsleyite and ringwoodite are thought to dominate the transition zone of the mantle, a zone present from about 410 to 660 km
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