Fayalite


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Related to Fayalite: magnetite

fayalite

[fə′yä‚līt]
(mineralogy)
Fe2SiO4 A brown to black mineral of the olivine group, consisting of iron silicate and found either massive or in crystals; specific gravity is 4.1.

Fayalite

 

a mineral of the olivine group; the final member of the forsterite-fayalite solid-solution series. Fayalite has the chemical composition Fe2[SiO4], and it contains up to 10 percent of the forsterite component. It is found with acidic and alkalic rocks, metamorphosed iron-rich sediments, pegmatites, and other rocks. Fayalite is also detected in industrial slags.

References in periodicals archive ?
40]Ar datings on the Ocotal stock yield 78-80 Ma ages for well-preserved fayalite gabbros, one dolerite and separated fresh plagioclase from a ferrohortonolite-bearing gabbro.
Only a small amount of fayalite was available, so the crystals were crushed to powder between glass slides.
Fayalite then solidifies around the grains, gluing the sand onto the surface of the casting.
Associated minerals are: zircon, quartz, kainosite-(Y), aegirine, [beta]-fergusonite-(Y), yttrian ilvaite, ilvaite, hingganite-(Ce), neodymian allanite-(Ce), magnetite, fayalite and fluorite.
The role of iron oxide in preventing porosity has long been linked with its ability to react with silica to form fayalite, which forms a "physical" barrier, preventing gas solution.
The following standards were used: diopside (Si, Ca), spessartine (Mn), fayalite (Fe), andalusite (Al) and forsterite (Mg).
Most foundrymen were taught that seacoal acts by burning and producing a reducing atmosphere, which prevents oxidation of the cast iron, and consequently prevents the formation of fayalite and ultimately Penetration.
Standards used were pure niobium and tantalum metals (Nb, Ta), Rockport fayalite (Fe), Nuevo garnet (Mn) and Webster fosterite (Mg).
When comparing the Gibbs Free Energy of Formation for mullite, fayalite and tephroite, the reactions between the iron- and manganese oxides and the silica will have the following values:
Associated minerals are: fayalite, magnetite, quartz, annite, laihunite, and clinoamphiboles (only at the Colorado locality).
This leads to high levels of FeO in the bath, forming fayalite and other low-melting point slags that carry over into characteristic "bird shot" defects.
Associated minerals are: quartz, magnetite, spessartine-rich garnet, "apatite," sillimanite, ferroan gahnite, sulfides, Mn-rich grunerite (in places manganogrunerite), manganoan fayalite and Mn-rich pyroxferroite.