Seymchan Pallasite Full Slice, PMG, 308.40g, Translucent Olivine

About this specimen

This is a 308.40 g full slice of Seymchan, a pallasite recovered from the Magadan region of Russia. It is a complete cross section of the mass rather than a part slice cut from one. The Meteoritical Bulletin Database records the recommended classification as Pallasite, PMG, the find year as 1967, and the country as Russia. It is recorded as a find rather than an observed fall.

Seymchan is one of a small number of meteorites whose classification was formally overturned after decades on the books. It entered the literature in 1968 as an iron. It is on the books today as a main group pallasite. The material on this cut face is the reason why.

Structure and features

Olivine occupies a large proportion of the cut face, set in an iron nickel matrix. Under transmitted light a substantial share of those crystals pass light cleanly, running from pale gold through honey and amber into deep orange, with internal fracture planes and cleavage steps visible inside the better ones.

That transparency is the variable that separates one pallasite slice from another. Olivine in pallasites is often opaque, heavily fractured, or clouded by terrestrial weathering, and the proportion of light passing crystals differs from mass to mass and from cut to cut within a single mass. On this slice the light passing fraction is high enough that the specimen reads as an entirely different object backlit than it does in reflected light. The photographs above show it both ways.

Crystal outlines across most of the face are angular rather than rounded, and metal veins separate the denser olivine clusters. Both faces are complete, with the natural exterior margin of the mass running the full way around.

The metal is mirror polished and has not been acid etched, which is a deliberate choice on a slice cut for its olivine. Etching develops the Widmanstatten pattern in the metal, but it does so by leaving the surface matte and grey. A mirror polish keeps the matrix bright and reflective, which is what a face like this one needs: light entering the olivine has a reflective surround behind and between the crystals rather than a dulled one. Buyers who want the etched structure should look to an iron rather than to this slice.

Both faces carry a light epoxy coating applied as a moisture barrier. It is thin, it does not obscure the olivine or the metal, and it is ordinary practice for iron bearing meteorites intended for open display. Handling and storage guidance is set out in how to care for and store a meteorite, and the underlying issue is covered in do meteorites rust.

Discovery and provenance

The Meteoritical Bulletin writeup, published as Meteoritical Bulletin no. 43 in Moscow in 1968 and reprinted in Meteoritics 5, 85 to 109 in 1970, records the discovery in detail. The meteorite was found in a brook bed flowing into the river Hekandue, a left tributary of the river Jasachnaja, in the Magadan district. Two individual specimens were recovered. The larger was found in June 1967 by the geologist F. A. Mednikov during a geological survey, lying among the stones of the brook bed. The smaller was found at a distance of 20 m from the first by I. H. Markov with a mine detector in October 1967. The writeup records that the main mass was turned over to the Academy of Sciences of the USSR.

Recorded coordinates are 62 degrees 54 minutes N, 152 degrees 26 minutes E. Seymchan is one of 6 approved meteorites from Magadanskaya oblast, Russia.

This specimen was acquired by Treasure Coast Meteorite Co. and cut and prepared for sale. It carries serial TC-00039 and a permanent specimen record page.

Scientific context

The classification history in the Bulletin database reads as a sequence. Meteoritical Bulletin 43 in 1968 recorded it as Iron. The NHM Catalogue 5th Edition in 2000 recorded it as IIE. MetBase version 7.1 in 2006 recorded it as Iron ungrouped. The recommended classification is Pallasite, PMG. The database comments field records the reclassification against van Niekerk et al. (2007), with a revision dated 26 May 2009 covering revised pallasite classifications.

The 2007 abstract behind that change, Seymchan: A Main Group Pallasite, Not an Iron Meteorite, presented at the 70th Annual Meteoritical Society Meeting, sets out the reasoning. A 2004 expedition to the same locality recovered further masses. The abstract notes reports that roughly 20 percent of those newer finds were pallasitic or partly pallasitic, with the remainder iron. Oxygen isotope analysis of the silicate placed the material inside the main group pallasite field, and the metal composition matched the original iron masses. A meteorite described for forty years from metal alone turned out to be heterogeneous, and the pallasitic portion had simply not been sampled first.

Pallasites have long been interpreted as material from the boundary region between the metallic core and the silicate mantle of a differentiated asteroid, though the formation setting remains under active debate in the literature. Background on the class is set out in what is a pallasite, and the way classifications like this one are assigned and revised is covered in how are meteorites classified.

Seymchan is one of 79 approved meteorites classified as Pallasite, PMG, as recorded in the Meteoritical Bulletin Database in September 2026.

Frequently asked questions

Why was Seymchan reclassified from an iron meteorite to a pallasite?
Because the first two masses recovered in 1967 were metal. A 2004 expedition to the same locality recovered further masses, some of them olivine bearing. Oxygen isotope work on that silicate placed it in the main group pallasite field while the metal chemistry matched the original irons, establishing that the meteorite is heterogeneous rather than that two meteorites had been confused. The Bulletin database records the reclassification against van Niekerk et al. (2007).

Is the olivine on this slice actually translucent?
Yes, across a large share of the face. The backlit photographs above are of this specific slice and are not stock images. Not every crystal transmits, and the darker crystals stay dark, which is normal for the material.

Does this slice show a Widmanstatten pattern?
No. The faces are mirror polished and have not been acid etched, so the metal reads as a bright reflective matrix rather than a patterned one. This is stated plainly because it is a preparation choice rather than an oversight. Etching would develop the pattern at the cost of a matte grey surround for the olivine, and on a slice whose value sits in the transparency of its crystals that is the wrong trade.

What is the epoxy coating for?
It is a thin moisture barrier. Iron bearing meteorites take up atmospheric moisture and can corrode over time without protection. The coating is light enough that it does not change the appearance of the olivine or the metal, and it is disclosed here rather than left to be discovered.

Was Seymchan seen to fall?
No. The Bulletin database records it as a find, with a find year of 1967.

What documentation comes with it?
A certificate card bearing serial TC-00039, and a permanent specimen record page on this site giving the identification and classification data, the recorded weight, and photographs of this specimen. The serial is an index to that record.

Collector significance

Seymchan is available material, and small slices of it are not difficult to find. Large slices carrying a high proportion of light passing olivine are a narrower proposition, because the olivine content varies across the meteorite and the transparency of that olivine varies again on top of it. At 308.40 g this sits well above the size at which pallasite material is usually offered, and the backlit face is the reason to want it rather than an incidental feature of it.

It is also a full slice. Most pallasite on the market is part slice material cut from the interior of a mass, which shows the olivine but not the shape of the stone it came from. A complete cross section carries the natural margin the whole way around and can be read as a section through a specific object rather than as a sample of a meteorite. Full slices at this weight are a much smaller pool than part slices at the same weight.

It also carries an unusually legible piece of scientific history. Reclassifications of this kind are infrequent, and the paper trail is public, dated, and citable rather than anecdotal. A buyer can follow the classification from Iron in 1968 to Pallasite, PMG today through the database record itself.

Offered by Treasure Coast Meteorite Co., IMCA Member #3323, Hobe Sound, Florida. Further pallasite and iron material is listed in the stony iron meteorite collection. Classification data on this page is reproduced from the Meteoritical Bulletin Database entry for Seymchan, maintained by the Nomenclature Committee of the Meteoritical Society and hosted by the Lunar and Planetary Institute. How that database works and what its entries record is explained in understanding the Meteoritical Bulletin.