fayalite

The olivine is a solid solution of 11 to 40% fayalite with the rest being forsterite.

In addition, fayalite can react with oxygen to form magnetite:

Moreover, gas atmosphere in early furnaces is much less reducing and fayalite may not be able to form in this condition.

For example, monticellite and pyroxene would form when fayalite can not take more CaO into it.

Olivine is a solid solution between the magnesium-endmember forsterite and the iron-endmember fayalite.

A textbook example of a eutectic phase diagram is that of the olivine (forsterite and fayalite) system.

Tridymite, fayalite and other minerals in the lithophysae may be precipitates from the vapor phase that occupied the cavities.

Green Sand for aluminum typically uses olivine sand (a mixture of the minerals forsterite and fayalite which are made by crushing dunite rock).

Serpentinite reactions 1a and 1b, below, exchange silica between forsterite and fayalite to form serpentine group minerals and magnetite.

If an olivine composition contains sufficient fayalite, then olivine plus water can completely metamorphose to serpentine and magnetite in a closed system.

The name fayalite is derived from Faial (Fayal) Island in the Azores where it was first described in 1840.

Serpentinisation reaction, involving also the transformation of fayalite (Fe-end member of olivine) into magnetite, quartz and hydrogen:

Mafic minerals may include aegirine, fayalite, aenigmatite, ilmenite, and sodic amphibole (often arfvedsonite or ferrorichterite).

"Notes on crystals of scapolite, gypsum, and fayalite..." Johns Hopkins University Circular, pp.

Forsterite has an unusually high melting temperature at atmospheric pressure, almost 1900 C, but the melting temperature of fayalite is much lower (about 1200 C).

Knebelite is a silicate mineral, a manganese variety of fayalite with formula (Fe,Mn)SiO.

The maskelynite is zoned, with accessory phases of titanomagnetite, ilmenite, pyrrhotite, fayalite, trydimite, whitlockite, chloraptite, and baddeleyite.

The temperature at which the liquidous phases crystallize in a sequence: mullite + tridymite, followed by sekaninaite and finally fayalite + clinoferrosilite (Grapes, 2010).

Nearly pure fayalite is a minor constituent in some granite-like rocks, and it is a major constituent of some metamorphic banded iron formations.

The ratio of magnesium and iron varies between the two endmembers of the solid solution series: forsterite (Mg-endmember) and fayalite (Fe-endmember).

In the olivine structure, the main olivine series of (Mg, Fe)SiO consist of magnesium-rich forsterite and iron-rich fayalite.

The bottom of the furnace also fills with molten slag, often consisting of fayalite, a compound of silicon, oxygen and iron mixed with other impurities from the ore.

It also occurs in the Earth's crust, in association with clinopyroxene, plagioclase, ilmenite, cristobalite, tridymite, fayalite, fluorapatite and potassic feldspar, and forms series with pyroxmangite.

Other examples of series include the olivine series of magnesium-rich forsterite and iron-rich fayalite, and the wolframite series of manganese-rich hübnerite and iron-rich ferberite.

These Fe-rich paralavas are composed of Fe-olivine, esseneite, dorite, melilite, Fe-cordierite, anorthite, spinel, tridymite, fayalite, magnetite, quartz etc. (Novikova, 2008).