Mesosiderites are enigmatic mixtures of metal and igneous rock. Catastrophic collisions more than four billion years ago may explain this unexpected mingling of nickel-iron alloy from the core and rock from the surface of one or more large asteroids. The coarse Widmanstätten structures in the metal suggest that it cooled very slowly, probably because the rock-metal mixture was deeply buried following melting and mixing.

Mount Padbury is a mixture of dark rock fragments from an asteroid’s deep interior and shiny metal droplets with Widmanstätten patterns from a core. They are surrounded by basaltic material from the surface.