Aletai Iron Meteorite Slice, IIIE-an Octahedrite, 334.12g, Etched Widmanstatten Pattern

Etched IIIE-an iron from an asteroid core

This 334.12g Aletai slice is cut from one of the iron masses of the Aletai meteorite and is etched on both faces to bring out the Widmanstätten pattern across the full cross section. Aletai is an iron meteorite of the anomalous IIIE group. Its interlocking kamacite and taenite bands formed during slow cooling in the metallic core of a differentiated asteroid. Etching with dilute acid dissolves kamacite faster than taenite, raising the taenite in relief and giving the geometric banding its visible contrast from edge to edge.

The slice carries the structural pattern across both etched faces, with natural exterior edges preserved around the cross section. Aletai was recovered from the Altay region of Xinjiang, China, and was formally established under that single name by the Meteoritical Society in 2016, drawing together several large iron masses that had previously been recorded under separate names. The result is a specimen with both a published scientific classification and a long, documented discovery history.

Widmanstätten structure and inclusions

The Widmanstätten pattern on this slice reflects the three-dimensional arrangement of kamacite plates within taenite, an octahedral geometry that develops only under cooling rates measured across millions of years. Aletai is an iron meteorite of the anomalous IIIE group, with a kamacite bandwidth published in the Meteoritical Bulletin of roughly 0.9 to 1.0 mm. The intersecting angles of the lamellae trace the octahedral symmetry of the original metal crystal.

Across the etched face you can see darker linear and rounded features set into the metal. Per the published classification, Aletai carries minor phases that include schreibersite, troilite, daubréelite, and haxonite alongside its kamacite and taenite, and inclusions of this kind are part of the recorded petrography for the meteorite. Each slice differs in how these features are distributed, so the face shown in the photographs is specific to this 334.12g piece.

Discovery in Xinjiang and the Aletai strewn field

The first Aletai mass was found in 1898 in the Altay region of the Xinjiang Uyghur Autonomous Region in northwestern China. Over the following century, additional iron masses were located across the same area, recorded at the time under names such as Armanty, Wuxilike, Akebulake, and Ulasitai. Chemical and petrographic analysis later showed these irons to be paired, that is, fragments of a single fall.

In 2016 the Meteoritical Society unified the paired masses under the single official name Aletai, abolishing the earlier names as synonyms. The masses lie along a northwest to southeast array spanning roughly 425 km across China, one of the longest strewn fields recorded for any meteorite. This slice is a sample of that fall, which was submitted to the Meteoritical Bulletin by Weibiao Xu and John T. Wasson.

An anomalous IIIE iron

Iron meteorites are sorted into chemical groups from trace element abundances measured by neutron activation analysis, combined with the etch structure seen on polished faces. Aletai belongs to group IIIE but is classified as anomalous, written IIIE-an, because its composition sits apart from the rest of the group. Published analyses note that Aletai carries the highest gold concentration among IIIE irons, with an iridium content above what the group trend would predict.

As of June 2026, the Meteoritical Bulletin lists Aletai as 1 of 2 approved meteorites classified as Iron, IIIE-an. Irons of this kind represent the cores of asteroids that melted and separated into metal and rock early in solar system history, then were broken apart by later collisions. For broader background on this crystal structure, see our guide to the Widmanstätten pattern explained, and for additional context the Meteoritical Society maintains the official record of meteorite names and classifications.

Frequently asked questions

Is this meteorite authenticated? Aletai is classified in the Meteoritical Bulletin as an anomalous IIIE iron (IIIE-an) from Xinjiang, China. You can verify the classification through the official Meteoritical Bulletin entry. This specimen ships with a Treasure Coast Meteorite Co. certificate of authenticity documenting its classification and provenance.

What does IIIE-an mean? IIIE is a chemical group of iron meteorites defined by trace element composition. The suffix an is short for anomalous, indicating that Aletai's chemistry falls outside the normal IIIE range while still belonging to the group.

What is included with this specimen? This listing includes the 334.12g Aletai slice, etched on both faces, and a certificate of authenticity. No display stand is included unless noted in the listing. The cube shown in one photograph is a 1 cm scale reference and is not part of the sale.

How is the slice prepared? The piece has been cut from the parent mass, polished, and etched with dilute acid on both faces to reveal the internal crystal structure. Etching removes kamacite faster than taenite, creating the relief that makes the Widmanstätten pattern visible.

Do iron meteorites need any care? Metallic iron can oxidize in humid conditions. Keep the slice in a low-humidity environment, avoid bare-hand contact with the etched faces, and store with silica gel desiccant if possible. Many collectors apply a thin protective coating to preserve the etched contrast.

Collector significance

Aletai brings together a published anomalous IIIE classification, an etched Widmanstätten structure with well-defined bands, and a discovery history tied to one of the longest strewn fields on record. The combination of documented science and provenance gives the meteorite standing with collectors who value both display quality and a clear paper trail.

At 334.12g, this full slice is large enough to show the pattern clearly across both faces while remaining practical for cabinet or desktop display. It is offered by Treasure Coast Meteorite Co., IMCA Member #3323, with documented classification and provenance. Browse additional classified irons in our Iron Meteorites collection.

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