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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 mineral olivine (/ ˈ ɒ l. ɪ ˌ v iː n /) is a magnesium iron silicate with the chemical formula (Mg,Fe) 2 Si O 4.It is a type of nesosilicate or orthosilicate.The primary component of the Earth's upper mantle, [9] it is a common mineral in Earth's subsurface, but weathers quickly on the surface.
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.
The most abundant minerals are olivine and hypersthene (an orthopyroxene), as well as iron–nickel and troilite. Chromite, sodium-rich feldspar and calcium phosphates occur in minor amounts. Petrologic type 6 dominates, with over 60% of the L chondrites falling into this class. This indicates that the parent body was sizeable enough (greater ...
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.
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
Serpentine minerals are often formed by the hydration of olivine-rich ultramafic rocks at relatively low temperatures (0 to ~600 °C). [15] The chemical reaction turns olivine into serpentine minerals. They may also have their origins in metamorphic alterations of peridotite and pyroxene.
Other observed textural features that are clearly the result of very rapid cooling are dendritic and hopper-shaped olivine grains, and chondrules that are composed entirely of glass. More commonly, chondrules display what is known as a porphyritic texture. In these, grains of olivine and/or pyroxene are equidimensional and sometimes euhedral.