Seymchan Meteorite

Описание: Seymchan pallasite, also known as Suicheng pallasite in Chinese, belongs to the PMG Main Group Pallasites. Renowned for its heterogeneous mixture of metal and olivine and unique aqueous alteration features, it is a rare stony-iron meteorite with both significant scientific research and collectible value. Below are its core details:

I. Core Basic Information

● Official International Name: Seymchan, cataloged with Meteoritical Bulletin No. 2438 by the Meteoritical Society

● Discovery: June 1967, in the dry riverbed of the Kharkandyu River near the town of Seymchan, Magadan Oblast, Russia. Geologist F.A. Mednikov discovered the main mass weighing approximately 272.3 kg, with an additional 51 kg fragment found in October of the same year. New samples have been continuously recovered since 2004, with a cumulative total weight of about 351 kg; the largest subsequent specimen discovered weighs around 2.67 tons.

● Coordinates: 62°54′N, 152°26′E

● Classification Change: Initially classified as an IIE iron meteorite due to sampling limitations, it was re-identified and corrected to a PMG Main Group Pallasite in 2007.

II. Classification and Composition

● Classification: PMG Main Group Pallasite, a rare subclass of stony-iron meteorites with transitional characteristics of the asteroid core-mantle boundary

● Composition: Composed of chrysolite (translucent golden-green olivine, with the largest single crystals reaching several centimeters) and iron-nickel alloy (kamacite and taenite), with minor minerals including troilite and schreibersite. It has a nickel content of approximately 8–10% and contains characteristic trace elements such as gallium, germanium and iridium, with an unusually high iridium content making it a distinctive type of pallasite.

● Aqueous Features: Some samples contain aqueous alteration minerals (e.g., goethite, ferrihydrite), which record traces of water-rock interaction either in space or after the meteorite's fall, making it an important sample for studying the aqueous processes of meteorites.

III. Core Characteristics and Value

● Visual Highlights: Heterogeneous texture, with some areas showing dense olivine crystals embedded in a silvery-white iron-nickel mesh and others consisting of nearly pure metal. Polished and pickled surfaces reveal distinct Widmanstätten patterns; it has a density of approximately 7.5–7.8 g/cm³ with a notably heavy heft, and the olivine exhibits an amber luster, boasting high ornamental value.

● Scientific Research Value: Formed at the asteroid core-mantle boundary, it preserves records of the early core-mantle differentiation process of the solar system. Its aqueous alteration features provide key data for studying meteorite-water interactions and the origin of water in the solar system.

● Collectible Value: A highly sought-after pallasite among collectors due to its unique texture, exquisite appearance and limited stock. High-quality specimens are valued from several thousand to ten thousand RMB per gram.