Crystals in cross section
The crystal structure in iron meteorites is three-dimensional, so the pattern looks different depending on how you slice it. These meteorites have been cut with a saw and polished flat to reveal the crystals in cross section.
The actual 3-D structure is made of numerous flat plates of the iron-nickel alloy kamacite. When molten iron and nickel first cool and harden in a planet's core, they form a different alloy, taenite. But as the solid taenite cools, plates of crystallized kamacite grow through it. After millions of years, when the metal cools so much that crystals stop growing, the finished pattern freezes in place.
Topic: Earth Science
Keywords: Astrogeology, Astrophysics, Crystals, Iron-nickel alloys, Meteorites, Iron, Mineralogy