COMPARING INVESTIGATIONS ON THE SURFACE STRUCTURES OF IRGHIZITES AND PYROCLASTICS BY SEM

The surface structures of irghizites from the Zhamanshin crater in Kazachstan, USSR, play an important role in the discussion of their genesis. These surface structures were compared with those of typical tektites (australites) and pyroclastics (obsidians, lapilli) based on investigation by electron microscope. The results of these investigations indicate that there are no unambiguous genetical relationships between the morphology of irghizites and the surface features of tektites and pyroclastics. The surface shapes of irghizites result from several simultaneous or successive processes, in the course of which globules of different size melted, stuck together and were eaten into by corrosive gases after their solidification. The assumption that the verrucose swellings were caused by expanding gas bubbles immediately below the surface of the glass bulk can be excluded. The verrucose glass globules are identical in chemical composition to the glass bulk of the irghizites.