A characteristic cross-hatched pattern that becomes visible on the surface
of octahedrites (the commonest type
of iron meteorites) and pallasites
after polishing and etching with nital (nitric acid in solution with ethanol).
It is due to an intergrowth of crystals of nickel-rich
taenite and nickel-poor kamacite and is formed when the liquefied outer surface of an iron meteorite cools on entering the Earth's atmosphere.
It is named after its discoverer, the Austrian mineralogist Alois von Beckh
Widmanstätten (1754–1849), who observed them in 1808.