Mössbauer studies of natural glasses of impact and volcanic origin

Mössbauer spectroscopy of natural silicate glasses of impact (tektites, impactites, and irghizites) and volcanic origin (obsidians) is performed. The resulted spectra are processed by the method of reconstructing the distribution functions of superfine parameters of partial spectra. The content of Fe$^{3+}$: is determined to be 5–10% in tektites, 15–25% in impactites, 25–35% in irghizites, and ∼20% in obsidians. The oxygen coordination sphere of Fe$^{3+}$ is found to be octahedral in the tektites, tetrahedral in the impactites, and intermediate in the other glasses. The coordination of Fe$^{2+}$ is intermediate between the octahedral and pentahedral ones.