Complete Slice of Seymchan Meteorite

Pallasites represent fewer than 0.2% of all known meteorites and are widely considered to be the most beautiful extraterrestrial substances known. Like the vast majority of pallasitic meteorites, Seymchan originated from the mantle-core boundary of an asteroid that broke apart during the early history of the solar system. Following pinball-like impacts, a portion was serendipitously bumped into an Earth-crossing orbit.

The crystals seen here are the result of small chunks of the asteroid's stony mantle becoming suspended and crystalizing in the molten metal of its iron-nickel core. Cut and polished, the lustrous metallic matrix features silicate crystals of gleaming olivine and peridot (gem-quality olivine) ranging in hues from deep green to shimmering amber. The prominent metallic latticework found throughout the slice is referred to as a Widmanstätten pattern, and is the result of slow cooling, over millions of years, that provided sufficient time for the two iron-nickel allows present to orient into a crystalline habit. As the only place where this can happen is within differentiated asteroids in the vacuum of space, the appearance of this pattern is diagnostic in the identification of a meteorite. As the crystals are not homogeneously scattered throughout the metallic matrix, Seymchan is referred to as a transitional pallasite, a much less common and more distinct presentation.