(the term used to describe an object that has been claimed to be a meteorite, but which is nonmeteoritic in origin)
Terrestrial origin
It was reported that at 3:30 P.M. on February 1, 1956, a bright fireball accompanied by a smoke train was witnessed over an area of 500 km² in the state of Perm in Russia. The fireball produced a loud detonation which rattled and broke windows in nearby buildings. This object was seen to fall into the ice-covered Shirokovsky water reservoir near the Kosva River (58° 48' N., 57° 57' E.), punching a 42-cm-deep hole through an 80-cm thickness of ice, finally coming to rest at the bottom of the 23-m-deep reservoir. Immediate attempts by divers to recover the meteorite were unsuccessful, it was reported. Not until early 2002, following three years of efforts, were hunters able to recover ~150 kg of fragments of an unusual pallasite-like mass.
Comprehensive analyses of this material, provisionally named Shirokovsky, were conducted by the following institutions: A. Nazarov, G. Kolesov, L. Kashkarov, and A. Ivliev at the Vernadsky Institute; L. Taylor at the University of Tennessee; D. Rumble, III at the Carnegie Institute; Y. Shukolyukov and L. Shultz at the Max-Planck Institute; T. Bunch and J. Wittke at Northern Arizona University. The Shirokovsky mass has been described as a melt-matrix breccia similar to a stony-iron meteorite, which contains angular olivine with a broad range of Fa values (Fa3–39), along with numerous types of inclusions such as diopside and Mg–Fe oxides, as well as some nesosilicate and oxide phases never before identified in meteorites. These are all embedded within a metallic matrix with 20–47 wt% Ni and 0.8–2.2 wt% Co.
The investigators detected an absence of the typical accessory phases present in stony-iron meteorites, including sulfide, phosphide, phosphate, chromite, and aluminum phases. This amalgam was evidently rapidly cooled and crystallized in an oxidizing environment. Trace element ratios, O-isotopes, noble gases, and TL studies are all consistent with a terrestrial (man-made) origin rather than a cosmic origin. A special statement released by the Meteorite Nomenclature Committee concludes that "[t]he petrology and geochemistry of this object strongly suggest that it has a terrestrial origin." The photos above and below show representative thin partial slices of the pseudometeorite Shirokovsky.
