Aletai Iron Meteorite Slice, IIIE-an, 186.60g, Etched Widmanstatten Pattern

A 186.60g etched slice of Aletai iron

This slice weighs 186.60g and was taken from one of the iron masses of the Aletai meteorite, then cut, polished, and etched on both faces so the Widmanstatten pattern shows across the whole cross section. Aletai is an iron meteorite of the anomalous IIIE group. The metal formed in the core of a differentiated asteroid, where it cooled slowly enough for kamacite and taenite to grow into the interlocking structure that the etch reveals.

The pattern appears because acid attacks kamacite more readily than taenite. The taenite stands a little higher after etching, and that small difference in height is what the eye reads as the bright geometric banding. The two faces of this slice each carry their own version of the pattern, and the natural exterior edges of the mass are left in place around the cut.

Reading the etched face

The bands are kamacite plates that grew along the planes of an octahedron within the surrounding taenite, which is why the lines meet at repeating angles across the face. The kamacite bandwidth on record for Aletai in the Meteoritical Bulletin is about 0.9 to 1.0 mm, and that figure sets how fine or broad the banding looks once the surface is etched.

Look closely and darker patches and lines break up the metal in places. The petrography recorded for Aletai lists schreibersite, troilite, daubreelite, and haxonite as minor phases beside the kamacite and taenite, and small features like these are part of that record. How they fall on the face is particular to this 186.60g slice, so the surfaces in the photographs are the ones you receive.

One fall, many masses, one name

Aletai comes from the Altay region of the Xinjiang Uyghur Autonomous Region in the far north of China. The first mass was found there in 1898, and more were recovered across the region over the following century under separate local names, including Armanty, Wuxilike, Akebulake, and Ulasitai. Study of the metal later established that these irons were paired, the broken pieces of one event.

In 2016 the Meteoritical Society gathered the paired masses under the single official name Aletai and set the older names aside as synonyms. The pieces trace a northwest to southeast line of about 425 km across China, which ranks among the longest strewn fields known for any meteorite. This slice belongs to that fall, which was submitted to the Meteoritical Bulletin by Weibiao Xu and John T. Wasson.

Where Aletai fits among iron meteorites

Iron meteorites are placed into chemical groups using trace elements in the metal, measured by neutron activation analysis and read alongside the etch structure. Aletai falls in group IIIE but carries the anomalous tag, written IIIE-an, because its chemistry sits outside the usual IIIE range. Among IIIE irons it holds the highest gold content on record, and its iridium runs higher than the group trend would suggest.

As of June 2026, the Meteoritical Bulletin lists Aletai as 1 of 2 approved meteorites classified as Iron, IIIE-an. Irons of this type are the metal cores of early asteroids that melted, settled into metal and rock, and were later shattered in collisions. For more on how the structure forms, see our guide to the Widmanstatten pattern explained. The official register of meteorite names and classifications is kept by the Meteoritical Society.

Frequently asked questions

Is this meteorite classified? Yes. Aletai appears in the Meteoritical Bulletin as an anomalous IIIE iron (IIIE-an) from Xinjiang, China, and you can check the classification against the official entry. The slice ships with a Treasure Coast Meteorite Co. certificate of authenticity that records its classification and provenance.

Why is it labeled IIIE-an and not just IIIE? IIIE is a chemical group of iron meteorites defined by trace element composition. The tag an stands for anomalous and shows that Aletai sits outside the normal IIIE range while still being placed in the group.

What will I receive? You receive the 186.60g Aletai slice, etched on both faces, with a certificate of authenticity. A stand is not included unless the listing states otherwise. The cube in one photograph is a 1 cm scale reference and is not part of the sale.

How was the surface prepared? The slice was cut from the parent mass, polished flat, and etched with dilute acid on both faces. Because the acid removes kamacite faster than taenite, the etched surface holds the relief that makes the Widmanstatten pattern visible.

How do I keep an iron meteorite in good condition? Iron can rust in damp air, so store the slice somewhere dry, handle the etched faces sparingly, and keep it with silica gel desiccant. A thin protective coating is a common step to hold the contrast of the etch over time.

For the collection

This slice carries a published anomalous IIIE classification, an etched Widmanstatten structure, and a strewn-field history that traces back to a documented source, the kind of record that supports both display and provenance. At 186.60g it sits well on a shelf or in a cabinet while still showing the full pattern on each face.

It is offered by Treasure Coast Meteorite Co., IMCA Member #3323, with documented classification and provenance. More classified irons are listed in our Iron Meteorites collection.

Meteoritical Bulletin entry: Aletai | Classification: Iron meteorite (IIIE-an) | Find, Xinjiang China, 1898