What is the X in X-mas?
any iron meteorite containing less than about 6 percent nickel (nickel-poor ataxites) or more than about 11 percent nickel (nickel-rich ataxites). Ataxites, containing plessite, troilite, and kamacite as their main minerals, show neither the Widmanstatten pattern nor Neumann lines. Nickel-poor ataxites generally have the same nickel content as hexahedrites but have a uniformly granular structure instead of large kamacite crystals. This structure is completely unrelated to that of the nickel-rich ataxites, which is a plessite-like intergrowth of taenite and kamacite; the ataxites that contain more than 27 percent nickel are composed of taenite instead of plessite.