Seymchan Pallasite Meteorite Full Slice, PMG, 591.00g, Widmanstätten Pattern

591g full slice from the iron-dominant zone with crisp Widmanstätten banding edge to edge

This 591.00g Seymchan full slice is cut from the iron-dominant zone of the mass, presenting no olivine. At approximately 20.3 x 16.5 cm, the Widmanstätten pattern reads across the entire face without interruption. Kamacite bands are sharply delineated throughout, the geometric interlocking structure is consistent from edge to edge, and there is no significant oxidation compromising the etched surface. The specimen is large enough that the crystal geometry registers at a glance rather than requiring close inspection.

Structure and features

The Widmanstätten pattern in this slice formed as the parent body cooled over millions of years deep inside a differentiated asteroid. The process produced an interlocking lattice of kamacite and taenite, two iron-nickel alloys that precipitate at different temperatures and lock into geometric bands as the system slowly equilibrates. The structure cannot be produced artificially and is one of the definitive indicators of iron meteorite authenticity. The banding width visible in this slice is consistent with Seymchan's structural identity as a coarse octahedrite, the classification it held prior to reclassification as a pallasite, and the geometry is uninterrupted across the full face.

Due to Seymchan's heterogeneous internal structure, specimens fall into two distinct categories: those from olivine-bearing zones containing silicate crystal clusters, and those from iron-dominant zones consisting almost entirely of nickel-iron metal. This slice is from the iron-dominant zone. Both zone types are scientifically documented within the same classified meteorite.

Scientific context

Seymchan was found in June 1967 by geologist F. A. Mednikov in the dry bed of the Hekandue river, a left tributary of the Yasachnaya in Magadan Oblast, Russia. The main mass of 272.3 kg was recovered during a geological survey. A second specimen of 51 kg was located nearby in October 1967. Both masses were turned over to the Academy of Sciences of the USSR. The meteorite was originally classified as an IIE anomalous coarse octahedrite.

In 2004, Dmitri Kachalin recovered additional material from the original find area, and approximately 20% of the new specimens were found to contain olivine crystals. This revealed the pallasitic nature of the mass. Van Niekerk et al. formally reclassified Seymchan as a pallasite in 2007. For further reading on pallasite formation and structure, see our guide: What Is a Pallasite?

Frequently asked questions

Is this meteorite authenticated? Yes. Seymchan is classified in the Meteoritical Bulletin as Pallasite, PMG. You can verify the classification here: Seymchan on the Meteoritical Bulletin Database. This specimen ships with a certificate of authenticity from Treasure Coast Meteorite Co. (IMCA #3323).

What does PMG mean? PMG stands for pallasite main group, the dominant chemical grouping among pallasites. Seymchan was reclassified from an IIE anomalous coarse octahedrite to PMG following the identification of olivine-bearing zones in recovered material studied by van Niekerk et al. (2007).

Why does this slice have no olivine if Seymchan is a pallasite? Seymchan is structurally heterogeneous. Some zones of the mass contain olivine crystal clusters; others consist almost entirely of nickel-iron metal. This slice is cut from an iron-dominant zone. Both zone types are authentic and represent the same classified meteorite.

What care does an etched iron meteorite slice require? Store in a low-humidity environment. Periodic application of Renaissance Wax or food-grade mineral oil to the etched face will slow oxidation. Avoid handling with bare hands and keep away from moisture sources.

What is included with this specimen? The 591.00g Seymchan full slice and a certificate of authenticity with full classification details from Treasure Coast Meteorite Co. (IMCA #3323).

Collector significance

Full slices of Seymchan at this size are not commonly available. Most material on the collector market comes as smaller partial slices, end cuts, or fragments. At 591g and over 20 cm in length, this specimen represents a substantial section of the mass. The full-slice format is what best displays Widmanstätten structure at scale, and in this specimen the geometry is uninterrupted from edge to edge with no significant oxidation or surface compromise. The iron-dominant zone is the material that most clearly expresses the structural identity established during Seymchan's original IIE octahedrite classification, and that structure is the primary visual feature of this slice.

Seymchan occupies a specific position in the collector market as a pallasite with two visually distinct specimen types from the same classified mass. Collectors working across meteorite categories often target both. This slice represents the iron-dominant type in a format and at a size that is increasingly difficult to source as original stock is cut down and dispersed.

Meteoritical Bulletin entry: Seymchan | Classification: Pallasite, PMG | Find, Russia, 1967