Aletai Iron Meteorite Slice, IIIE-an, 268.47g, Etched Widmanstatten Pattern

Etched iron from the Aletai strewn field

This 268.47g slice was cut from one of the iron masses of the Aletai meteorite, then polished and etched on both faces, so the Widmanstatten pattern runs across the full elongated cross section. Aletai is an iron meteorite of the anomalous IIIE group. Its metal crystallized in the core of a differentiated asteroid and cooled over millions of years, locking in the interlocking arrangement of kamacite and taenite that the etch later brings out.

Acid etching works because it dissolves kamacite faster than taenite. The taenite is left standing slightly proud of the surface, and that difference in relief is what makes the geometric banding visible from one edge of the slice to the other. Natural exterior edges are preserved around this cross section, and the two etched faces each carry the pattern in their own arrangement.

Widmanstatten pattern and inclusions

The banding on this slice traces the octahedral geometry of the original metal crystal, where kamacite plates grew along the faces of an octahedron within the surrounding taenite. The kamacite bandwidth recorded for Aletai in the Meteoritical Bulletin is roughly 0.9 to 1.0 mm, which sets the scale of the pattern seen on the etched face.

Set into the metal you can see darker inclusions, including an elongated body on one face and a seam that crosses the bands. Features of this kind are consistent with the petrography recorded for Aletai, which lists schreibersite, troilite, daubreelite, and haxonite as minor phases alongside the kamacite and taenite. Their distribution is specific to this 268.47g slice, so the faces shown in the photographs belong to this piece.

From the Altay region to a single classified name

The Aletai irons come from the Altay region of the Xinjiang Uyghur Autonomous Region in northwestern China, where the first mass was found in 1898. More masses were located across the same ground over the following century and were recorded under separate local names, among them Armanty, Wuxilike, Akebulake, and Ulasitai. Later analysis showed these irons to be paired, the scattered pieces of a single fall.

In 2016 the Meteoritical Society brought the paired masses together under the one official name Aletai and retired the earlier names as synonyms. The masses lie along a northwest to southeast line running about 425 km across China, among the longest strewn fields on record for any meteorite. This slice was cut from that fall, which was submitted to the Meteoritical Bulletin by Weibiao Xu and John T. Wasson.

What anomalous IIIE means

Iron meteorites are grouped from the trace elements in their metal, measured by neutron activation analysis and read together with the etch structure. Aletai sits in group IIIE but is marked anomalous, written IIIE-an, because its chemistry runs outside the ordinary IIIE range. Reported analyses give it the highest gold content among IIIE irons, with iridium above what the group trend alone would predict.

As of June 2026, the Meteoritical Bulletin lists Aletai as 1 of 2 approved meteorites classified as Iron, IIIE-an. Irons like this are the metal cores of early asteroids that melted, separated into metal and rock, and were later broken open by collisions. To read more about how the structure forms, see our guide to the Widmanstatten pattern explained. The Meteoritical Society holds the official record of meteorite names and classifications.

Frequently asked questions

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

What is the difference between IIIE and IIIE-an? IIIE is a chemical group of iron meteorites set by trace element composition. The added suffix an stands for anomalous and means Aletai's chemistry falls outside the normal range for the group while still belonging to it.

What comes with this slice? You receive the 268.47g Aletai slice, etched on both faces, together with a certificate of authenticity. A display stand is not included unless the listing says so. The metal cube in one photograph is a 1 cm scale reference only and is not part of the sale.

How was the slice finished? It was cut from the parent mass, polished, and etched with dilute acid on both faces. The acid removes kamacite faster than taenite, and the relief left behind is what makes the Widmanstatten pattern stand out.

How should an iron meteorite be stored? Iron can rust if it is left in damp air. Keep the slice somewhere dry, handle the etched faces as little as possible, and store it with silica gel desiccant. A thin protective coating is a common way to hold the etched contrast over time.

Collector notes

This piece pairs a published anomalous IIIE classification with an etched Widmanstatten structure and a documented strewn-field history, the combination collectors tend to look for when they want both display value and a clear record behind a specimen. At 268.47g the slice is sized for a cabinet or a shelf while still showing the full pattern across both faces.

It is offered by Treasure Coast Meteorite Co., IMCA Member #3323, with documented classification and provenance. You can find more classified irons in our Iron Meteorites collection.

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