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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.
Peridots can also be found in meteorites. Peridots can be differentiated by size and composition. A peridot formed as a result of volcanic activity tends to contain higher concentrations of lithium, nickel and zinc than those found in meteorites. [8] [full citation needed] Olivine is an abundant mineral, but gem-quality peridot is rather rare ...
Dunite is rarely found within continental rocks, but where it is found, it typically occurs at the base of ophiolite sequences where slabs of mantle rock from a subduction zone have been thrust onto continental crust by obduction during continental or island arc collisions . It is also found in alpine peridotite massifs that represent slivers ...
Olivine is the essential mineral found in all peridotites. It is an iron-magnesium orthosilicate with the variable formula (Mg,Fe) 2 SiO 4. The magnesium-rich olivine of peridotites is typically olive-green in color. [20]
The distinctive characteristic of olivine lamproites is phlogopite macrocrysts and microphenocrysts, together with groundmass micas that vary in composition from phlogopite to "tetraferriphlogopite" (anomalously Al-poor phlogopite requiring Fe to enter the tetrahedral site). Resorbed olivine macrocrysts and euhedral primary crystals of ...
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. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian.
Forsterite is the main olivine endmember most consistently found in samples of the Blue Ridge Ophiolite. [4] Other minerals found in noticeable amounts in the formation are orthopyroxene, clinopyroxene, and chromite. [4] In rare cases garnets and plagioclase can be found in some samples. [1] Unaltered samples of the Blue Ridge Ophiolite are ...
In contrast, picrites are magnesium-rich because crystals of olivine have accumulated in more normal melts by magmatic processes. [1] Picrite basalt is found in the lavas of Mauna Kea and Mauna Loa in Hawaiʻi, Curaçao, in the Piton de la Fournaise volcano on Réunion Island and various other oceanic island volcanoes.