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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.
Orange forsterite with a portion of tephroite. Pure forsterite is composed of magnesium, oxygen and silicon. The chemical formula is Mg 2 SiO 4.Forsterite, fayalite (Fe 2 SiO 4) and tephroite (Mn 2 SiO 4) are the end-members of the olivine solid solution series; other elements such as Ni and Ca substitute for Fe and Mg in olivine, but only in minor proportions in natural occurrences.
Talc dominantly forms from the metamorphism of magnesian minerals such as serpentine, pyroxene, amphibole, and olivine, in the presence of carbon dioxide and water. This is known as "talc carbonation" or "steatization" and produces a suite of rocks known as talc carbonates.
Recognizing the habit can aid in mineral identification and description, as the crystal habit is an external representation of the internal ordered atomic arrangement. [1] Most natural crystals, however, do not display ideal habits and are commonly malformed. Hence, it is also important to describe the quality of the shape of a mineral specimen:
Serpentinization is a hydration and metamorphic transformation of ferromagnesian minerals, such as olivine and pyroxene, in mafic and ultramafic rock to produce serpentinite. [1] Minerals formed by serpentinization include the serpentine group minerals (antigorite, lizardite, chrysotile), brucite, talc, Ni-Fe alloys, and magnetite.
The process of alteration from mafic minerals to serpentine group minerals is called serpentinization. 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.
A monoclinic mineral, clinohumite is typically a dark to light brownish or orangy yellow, somewhat resembling the hessonite variety of grossular. [8] Clinohumite's crystal habit is usually granular, but may also be prismatic; crystals are almost always small. Simple and multiple crystal twinning (on {001}) is common, resulting in a highly ...
Monticellite and kirschsteinite (commonly also spelled kirschteinite [3]) are gray silicate minerals of the olivine group with compositions Ca Mg Si O 4 and CaFeSiO 4, respectively.. Most monticellites have the pure magnesium end-member composition but rare ferroan monticellites and magnesio-kirschsteinite are found with between 30 and 75 mol.% of the iron end memb