Ataxite
| Ataxite | |
|---|---|
| — IAB or others | |
| Composition | Mainly Meteoric iron, nickel (>18%), no Widmanstätten patterns |
 A phase diagram showing the link between structural and chemical classification. | |
.jpg)
Ataxites (from Greek meaning "without structure") are a structural class of iron meteorites with a high nickel content and show no Widmanstätten patterns upon etching.
Characteristics
Ataxites are composed mainly of
exsolved from taenite only at such a low temperature (below about 600°C) where diffusion is already too slow.[2]
Classification
Most ataxites belong to the
IAB group and fall into the sHL (high-Au, low-Ni subgroup), sLH (low-Au, high-Ni subgroup), sHH (high-Au, high-Ni subgroup) and "ung" subgroup (does not fit any subgroup of IAB). Only a couple of ataxites have been classified into the IAB complex and the IIF, IVA, IIAB, IIIAB groups.[3]
Abundance
They are a rare class, with none of the about 50 observed iron meteorite falls being an ataxite, however, the largest meteorite ever, the Hoba meteorite (found 1920 in Namibia, weight 60 tons), belongs to this class. A Tibetan Buddhist statue, the Iron Man, was likely carved from an ataxite meteorite. It might even be made from a fragment of the Chinga meteorite.[4][5] Other examples of ataxites are the Dronino meteorite and pieces of the Gebel Kamil.
See also
References
- ^ Vagn F. Buchwald, Handbook of Iron Meteorites. University of California Press, 1975
- ^ F. Heide, F. Wlotzka, Meteorites, Messengers from Space, Springer-Verlag 1995, page 143
- ^ "Meteoritical Bulletin Database". Meteoritical Society. Retrieved 18 December 2012.
- ^ "ncient Buddhist Statue Made of Meteorite, New Study Reveals". Science Daily. Retrieved 26 December 2012.
- .