A class of stony-iron meteorite, apparently related to the howardites. Mesosiderites resemble lunar surface breccias, and were apparently formed on the surface of their parent body by impact processes. They consist of fragments of eucrite and diogenite material, mixed with a large proportion of metallic nickel–iron alloy (typically 40–60% by mass). Their textures indicate that they were subjected to shock melting and metamorphism at temperatures up to 1000°C. Their parent body remains unknown. See also Basaltic Achondrite.