Pallasite meteorite, PMG. Magadan district, Russia, first known 1967. Polished part slice with extraterrestrial gems. Weighing 129.8 grams and measuring 67 mm x 67 mm x 4 mm. Seymchan is the meteorite that kept on getting more interesting as time went on. First discovered during the summer of 1967 by the Russian geologist F. A. Mednikov, it was originally classified as an IIE iron meteorite. In the early 2000s, meteorite hunters associated with the Vernadsky Institute in Moscow returned to the site in the hope of finding additional specimens. They did. And they were encrusted with olivine crystals. Their finds resulted in a rare classification change in the scientific literature: in 2007 van Niekerk et al. revised the designation for Seymchan from iron to pallasite.
Seymchan has an unusual structure: some areas display olivine-rich clusters, while others consist almost entirely of nickel-iron. During its tumultuous flight through the atmosphere and subsequent impact, it is easy to imagine the meteoritic masses of Seymchan shearing at the nickel-iron/olivine borders. Some pieces, therefore, appear to be entirely metallic, while others appear pallasitic. This explains why Mednikov found what he assumed to be an entirely iron, or sideritic meteorite, while later expeditions found what they assumed to be pallasites. Similar instances of pallasite meteorites from the same fall exhibiting different features from one mass to another have been seen in the Brenham, Kansas meteorite [SEE LOT 2449]. This square-cut part slice is polished on one side and etched with nitol on the other, to reveal its shimmering Widmansta¨tten Pattern. Small, luminous, richly-colored olivine (peridot) crystals are suspended in a shiny nickel-iron matrix.
