MARE METEORITICS

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Irghizite


Name: Irghizite
Location: Zhamanshin Crater, USSR

The irghizite glass is found at the Zhamanshin crater, the impact origin of which is beyond serious doubt. It is associated with impactites (called zhamanshinites) which contain coesite, stishovite, maskelynite and melted foamed silica. Yu. F. Pogrebyak found that the elements Ni, Co. and Cr occur in irghizites at levels so much above the levels in the country rock that there can be little doubt that these elements must have come from the projectile that made the crater. It follows that the projectile could not have been an iron meteorite nor a stony-iron. We are forced to conclude that the projectile at Zhamanshin probably did not belong to any of the types of objects classed as meteorites in the strict sense. Could it have been a comet? It is concluded that the geochemical data are consistent with the hypothesis of a giant tektite as the projectile at Zhamanshin, and are not consistent with any kind of non-glassy meteorite. In this case both the irghizites and the zhamanshinite spray might have been produced at the contact between the projectile and the ground.

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