1. Fig. 2 Micro-Raman spectroscopy and mapping of an amygdaloidal silica micrograin in the breccia matrix.
Micro-Raman spectroscopy and mapping of an amygdaloidal silica micrograin in the breccia matrix. (A) High-magnification BSE image of an amygdaloidal silica micrograin (no. 1) in the breccia matrix of NWA White crosses indicate the analytical points for Raman spectroscopy (areas 1 to 3). (B) Raman spectra of areas 1 to 3 of the silica micrograin in (A) showing a negative correlation between the Raman intensities of the moganite and the quartz bands. Obvious coesite bands are present together with the moganite signature in the rim of the silica micrograin (area 2). a.u., arbitrary units. (C to E) Raman intensity maps of the moganite (502 cm−1) (C), coesite 21 cm−1) (D), and quartz (464 cm−1) (E) bands for the silica micrograin. Red and blue denote the high- and low-relative Raman intensities of each silica band, respectively. Moganite becomes dominant at the left part of the silica micrograin, whereas quartz is abundant in the right part. Coesite coexists with moganite and occurs in the outermost rim of the left, as indicated by the areas of overlap in the spectra.
Masahiro Kayama et al. Sci Adv 2018;4:eaar4378
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