Aletai Iron Meteorite Slice, IIIE-an, 161.49g, Etched Widmanstatten Pattern

A 161.49g Aletai slice, etched on both sides

This 161.49g slice comes from one of the iron masses of the Aletai meteorite. It has been cut from the mass, polished, and etched on both faces, so the Widmanstatten pattern reads across the full length of the cross section. Aletai is an iron meteorite of the anomalous IIIE group, metal that crystallized deep in the core of a differentiated asteroid and cooled across millions of years, long enough for kamacite and taenite to settle into the interlocking arrangement the etch later draws out.

Etching relies on a simple difference: dilute acid removes kamacite faster than taenite. The taenite is left raised in slight relief, and that relief is what the eye registers as the bright geometric bands. Both faces of this slice show the pattern, and the natural exterior edges of the original mass remain around the cut.

What the etch shows

Each band marks a kamacite plate that grew along a face of an octahedron set within the surrounding taenite, so the lines repeat at fixed angles wherever they cross the surface. For Aletai, the kamacite bandwidth recorded in the Meteoritical Bulletin runs about 0.9 to 1.0 mm, the figure that governs how the banding scales on the etched face.

Darker seams and patches interrupt the metal here and there, and a fracture runs through the slice with light oxidation along it. The petrography on file for Aletai records schreibersite, troilite, daubreelite, and haxonite as minor phases among the kamacite and taenite, and features of that sort sit within the metal. Their exact placement belongs to this 161.49g slice alone, so what the photographs show is the piece you receive.

Found in the Altay, paired across a strewn field

The Aletai irons were recovered from the Altay region of the Xinjiang Uyghur Autonomous Region in northern China, beginning with a mass found in 1898. More were located across the same region in the century that followed and were catalogued under separate local names, among them Armanty, Wuxilike, Akebulake, and Ulasitai. Analysis of the metal later tied these irons together as paired, the scattered remains of a single fall.

The Meteoritical Society unified those paired masses under the one official name Aletai in 2016 and retired the earlier names as synonyms. They lie along a northwest to southeast line of roughly 425 km across China, placing Aletai among the longest strewn fields recorded for any meteorite. This slice was cut from that fall, which was submitted to the Meteoritical Bulletin by Weibiao Xu and John T. Wasson.

An iron set apart within group IIIE

Chemical groups for iron meteorites come from trace element measurements in the metal, taken by neutron activation analysis and weighed against the etch structure. Aletai belongs to group IIIE, but it is recorded as anomalous, written IIIE-an, since its chemistry stands outside the normal IIIE range. It carries the highest gold content among IIIE irons on record, with iridium above the level the group trend predicts.

As of June 2026, the Meteoritical Bulletin lists Aletai as 1 of 2 approved meteorites classified as Iron, IIIE-an. Irons of this kind are the metal cores of asteroids that melted early in solar system history, separated into metal and rock, and were later broken apart in collisions. For a fuller account of how the structure forms, see our guide to the Widmanstatten pattern explained. The Meteoritical Society keeps the official record of meteorite names and classifications.

Frequently asked questions

Is this a classified specimen? Yes. Aletai is listed 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 does the an in IIIE-an mean? IIIE is a chemical group of iron meteorites set by trace element composition. The an marks the meteorite as anomalous, meaning Aletai sits outside the ordinary IIIE range while still being grouped with it.

What is included? You receive the 161.49g Aletai slice, etched on both faces, along with a certificate of authenticity. A display stand is not included unless the listing notes one. The cube in a photograph is a 1 cm scale reference 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. Since the acid takes kamacite faster than taenite, the etched surface keeps the relief that brings the Widmanstatten pattern into view.

What care does an iron meteorite need? Iron can rust in damp conditions. Keep the slice in a dry spot, limit handling of the etched faces, and store it with silica gel desiccant. A thin protective coating is a common way to preserve the contrast of the etch.

A note for collectors

This slice brings together a published anomalous IIIE classification, an etched Widmanstatten structure, and a strewn-field history that leads back to a documented source, which is the pairing of display and provenance that many collectors look for. At 161.49g it suits a shelf or cabinet and still shows the full pattern on both faces.

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

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