Medium and fine crystals
These medium- and fine-grained meteorites have much thinner crystals than the coarse-grained samples above. Finer patterns generally indicate higher nickel content, because nickel limits the growth of the kamacite crystals that produce the Widmanstätten pattern.
Finer crystals are also produced by faster cooling. Gibeon (below, left), for example, has smaller crystals than Owens Valley (below), even though it has slightly less nickel. The most likely explanation is that Gibeon cooled more quickly than Owens Valley—indicating that it came from a smaller parent body.
Hamilton County, Texas, USA
Topic: Earth Science
Keywords: Asteroids, Astrogeology, Astrophysics, Crystals, Iron-nickel alloys, Meteorites, Iron, Mineralogy