Seymchan

Found in a stream in Russia's Far East in 1967 and thought to be an ordinary iron – until pieces with gem-like crystals turned up decades later.

Key facts

Type

Stony-iron, pallasite (main group)

Fell or found

Found

Year

1967

Country

Russia (Magadan region)

Mass

first mass about 272 kg; many more masses found since

Official name

Seymchan

In June 1967 a geologist named F. A. Mednikov was working in the Magadan region of the Russian Far East, a remote land of mountains, forests and cold rivers. In the bed of a stream he came across a heavy, dark lump of metal. It turned out to be an iron meteorite weighing about 272 kilograms. It was named Seymchan, after a nearby settlement. A second, smaller mass was found the following year.

An iron with a secret

At first, Seymchan was classified as an iron meteorite, a piece of the metallic core of an asteroid. Its polished and etched slices showed the Widmanstätten pattern, an interlocking network of metal crystals typical of iron meteorites. For decades it was simply regarded as an unusual iron.

Then, in the early 2000s, new expeditions to the area using metal detectors found many more pieces. Some of them were surprising: as well as metal, they contained large crystals of the green-yellow mineral olivine. That made them pallasites, the rare stony-iron meteorites in which olivine is set in iron-nickel metal. Scientists re-examined the meteorite and concluded that Seymchan as a whole is a pallasite, belonging to the main group of pallasites, with some parts that are almost pure metal and others that are rich in olivine.

This was an important lesson. A single meteoroid can contain very different textures, and a few samples may not represent the whole.

What it reveals

Pallasites have long been thought to form where the metal core and rocky mantle of a melted asteroid met, although other formation ideas are also being explored. Seymchan's large metal-rich zones and olivine-rich zones show that the boundary between metal and stone in its parent body was not neat and simple. Some parts were dominated by metal, while others contained many crystals. Scientists study how the olivine crystals were rounded or broken, and how the metal cooled, to understand the history of this deep region.

A popular meteorite

The discovery surprised many collectors, who had long known Seymchan only as an iron. After the new finds, Seymchan became popular with collectors and jewellers. Its olivine-bearing slices are spectacular when polished and lit from behind, and its metal-only parts display a bold, attractive Widmanstätten pattern. Slices and small pieces are now found in many collections.

As with all meteorites, care is needed. Cutting and etching are skilled tasks done by specialists with proper safety equipment, and children should never cut, heat or use chemicals on rocks. In Russia, as elsewhere, laws govern the collection and export of meteorites, and finds of scientific importance should always be reported.

Why it matters

Seymchan shows how meteorite classification can change as more material is found and studied. It also gives scientists a large body of pallasite material showing a wide range of textures within a single fall. That variety helps researchers test ideas about how metal and silicate minerals came together inside early asteroids.

Its story is also a reminder of the importance of fieldwork, especially in such a challenging place. The Magadan region lies in permafrost country, where the ground stays frozen for much of the year, so the season for searching is short. The first mass was found by a geologist who was looking for something else entirely. The later finds came from teams who returned to the area with new tools and found what earlier visitors had missed.

When you see a slice of Seymchan glowing with olivine, remember that for decades scientists did not know these crystals existed in it. They were hidden in the gravel of a remote valley in the Russian Far East, waiting to be found.

Did you know?

See more

Seymchan in the catalogue