Fig. 3

Mid-IR spectra for CI chondrites Ivuna and Orgueil, and CI-like Y-82162 and Y-980115. Also shown are spectra from saponite, antigorite and olivine standard minerals. Ivuna and Orgueil spectra have a peak at ~9.9 μm and a doublet at ~23 μm from the Si–O stretching and bending modes (dashed black lines). Y-82162 and Y-980115 spectra have a broad peak at ~9.9 μm and intense peaks at ~11.2, ~16.5 and ~19.5 μm that are consistent with olivine (dashed grey lines)