Micro Raman spectroscopy of olivines in L6 chondrites: Evaluation of the degree of shock

We successfully detected a small shift in the wavenumber position of a Raman line near 820 cm−1 of olivines in the thin sections of L6 ordinary chondrites. This shift is probably due to residual stress. The wavenumber position of the same Raman line in a sample of Yamato (Y) 7304 (L6) olivine is 821.39 cm−1 and its full width at half maximum (FWHM) is 19.0 cm−1. For a Y7305 (L6) olivine sample, the wavenumber position is 820.48 cm−1 and its FWHM is 12.0 cm−1. The wavenumber position of the Raman line in the Y7304 olivine sample shifts significantly toward a larger wavenumber compared to that of the Y7305 olivine. The FWHM of the Raman line of the Y7304 olivine is significantly larger than that of the Y7305 olivine. These results suggest that Y7304 experienced a stronger impact shock than Y7305. The result of this Raman study is consistent with those of the profile analysis of the X-ray diffraction spots recorded using the Laue method with synchrotron radiation and of the observation of wavy extinction under an optical microscope. This technique of Raman spectroscopy may have potential for non-destructive and quantitative measurement of residual stress in minerals.