Ataxite

Work in Progress

Relatively rare variety of iron meteorite (designated type D) made almost entirely of taenite, a solid solution of Fe and 27 to 65% Ni. The Greek name means “without structure” and refers to the lack of a visible Widmanstätten pattern (spindles of kamacite are visible only microscopically).

“Iron meteorites containing >16% Ni nucleate kamacite at such low temperatures that large single crystals could not form over the 4.55 billion years of solar system history; they lack a Widmanstätten pattern and are called Ni-rich ataxites (i.e. without structure). The Ni-poor ataxites are hexahedrites or octahedrites reheated in massive impacts, or artificially after they fell on Earth.” https://www.sciencedirect.com/topics/earth-and-planetary-sciences/taenite

Need more info as “Classification and Properties of Iron Meteorites” (https://www.higp.hawaii.edu/~escott/Scott%20n%20Wasson%201976%20rev%20irons.pdf) says Fine plessite, generally some isolated kamacite platelets


Chinga ataxite Meteorite (lacks Widmanstätten beacuseof its Ni content). Image source: http://www.arizonaskiesmeteorites.com/Widmanstatten/.