Iron Meteorite – IIIABRoundup, Montana

The undulating exterior rim of this complete slice encompasses the metallic crystalline matrix of the Roundup meteorite. When rotated clockwise, this specimen bears a semblance to a fish. A large inclusion of gray troilite (iron sulfide) accents the mass. Modern cutting.
239 x 121 x 2 mm. (9½ x 4¾ x ⅛ in.) and 377.9 g. (¾ lbs)

A particularly rare meteorite. Found in 1990 in central Montana near the small town of Roundup, only one 17.8 kilogram mass of this meteorite was ever recovered. (By way of comparison, there are orders of magnitude of more material originating from the Campo del Cielo, Gibeon, Seymchan and Sikhote Alin events). This sample originated from the molten core of an asteroid residing between Mars and Jupiter that had been shattered by an enormously energetic collision; portions of the core eventually found their way to Earth. When cut and etched, Roundup exhibits a medium-octahedral latticework of its two primary alloys, kamacite and taenite. This exquisite natural design is known as a Widmanstätten pattern. As this pattern does not appear in man-made steel, its presence is diagnostic of iron meteorites. Different iron meteorites have different Widmanstätten patterns (e.g. see lot 1). An extended cooling rate of millions of years was required was required for this meteorite’s elements to arrange themselves into this crystalline structure.

Christie's would like to thank Dr. Alan E. Rubin at the Institute of Geophysics and Planetary Physics, University of California, Los Angeles for his assistance in preparing this catalog note.

Marlin Cilz Collection, Malta Montana