In Campbell and Poduska, 2020, we can find a study of polycrystalline carbonate minerals and their infrared spectra. "A quick and easy way" to investigate carbonate materials is to use infrared spectroscopy, "which is one of the most widely used forms of vibrational spectroscopy". The midinfrared (MIR) range is 400-4000 cm -1 , and it "corresponds to vibrations within single carbonate moieties. Even in crystalline calcite, MIR spectra show distinctive peak-broadening trends that are correlated with crystallinity differences arising from greater microstrain fluctuation values and smaller crystalline domain sizes" (Campbell and Poduska, mentioning . "Earlier theoretical work demonstrated that analogous crystallinity differences do indeed trigger systematic peak broadening trends" (Campbell and Poduska, mentioning . In , we find told that experimental studies of "calcite showed that v4 peak is the mode that softens (broadens) the most at high temperatures" (Xu et al., mentioning Xu and Poduska, 2014). It is interesting the broadening of the peak v4; however, in the RRUFF spectra given above, it is the v3 band which is huge and broad.