Single nugget of the extremely rare Fe-Si intermetallic mineral gupeiite (Fe3Si) from a locality in Russia (Nizhnii Tagil, Sverdlovsk Oblast, Russian Federation). Analyzed specimen. — Photo: David Hospital · CC BY-SA 4.0
Gupeiite
Gupeiite is an IMA-recognized mineral species in the native element class, with the chemical formula Fe₃Si.
It crystallizes in the cubic crystal system (space group Fm3m).
Key properties: specific gravity 7.29; Black streak; Metallic luster.
IMA symbol Gup, IMA status: approved, named in 1983.
Innermost in spheres, surrounded by nickel-iron minerals and their oxidation products, apparently of extraterrestrial origin, found in placers.
It is found associated with Xifengite, kamacite, taenite, magnetite, wüstite, maghemite.
The name refers to an eastern passageway, Gupeikou, of the Great Wall of China.