What does the inside of a meteorite look like?
It depends on the type: most stony meteorites are grey inside with metal flecks and tiny round grains, iron meteorites are solid metal that shows a crisscross pattern when etched, and pallasites hold olivine crystals in metal.
Break open an ordinary rock and it usually looks the same inside as out. A meteorite is different. Its black fusion crust is only a thin skin, often less than a millimetre thick, and it frames an interior that tells you what kind of meteorite you are holding.
Most meteorites are chondrites. Inside they are usually light to medium grey, speckled with bright flecks of iron-nickel metal and darker grains of iron sulfide. Look with a magnifying glass and you may see chondrules, small rounded grains, mostly less than a few millimetres across, that were once molten droplets floating in the young Solar System. In weathered specimens the metal grains are wrapped in brown rust haloes. Carbonaceous chondrites are darker, often almost black, and some, like Allende from Mexico, are dotted with irregular white patches called calcium-aluminium-rich inclusions, the oldest solids dated from the Solar System.
Iron meteorites are solid metal. A cut face looks like polished steel, but when a specialist etches it with a weak acid, many reveal the Widmanstätten pattern, a crisscross of interlocking metal bands that grew as the metal cooled extremely slowly. Pallasites look like stained glass: golden-green olivine crystals set in shining metal.
Achondrites, meteorites that melted on their parent body, can look like Earth's volcanic rocks. Eucrites from the asteroid Vesta are pale grey with fine crystals, while howardites are breccias, rocks made of broken angular fragments of different shades welded together. Experts see the inside by sawing a slice or grinding a small window, using proper equipment and safety measures. This is not a job for children, and acid etching should be left to experienced adults.