Specimen Calc2. (a) Optical image. (b) Visual map of the surface of the cut face after embedding and polishing. (c and d) Fourier Transform Infrared microspectroscopy in reflectance mode (FTIR-RM) protein and mineral maps (area under the amide and PO4 peaks, respectively) obtained from the whole specimen with 80 × 80 μm spatial resolution (SR). (e and f) FTIR-RM protein and mineral maps obtained from the boxed regions in (c) and (d) with 40 × 40 μm SR. (g) X-ray micro-computed tomography (μCT) 3D projection images rotated around the same plane that was mapped with FTIR-RM, silicon drift detector energy dispersive X-ray spectrometry (SEM/SDD-EDS) and quantitative backscattered electron imaging. (h) The cyan boxed region of the FTIR-RM mineral map (f) that was subsequently mapped with SEM/SDD-EDS. (i) SEM/SDD-EDS P, Ca, Na and Mg maps of the same region that was mapped before with FTIR-RM (h). A smaller size scale bar (100 μm) is shown in the P map to emphasize the small dimensions of many of the tiny calcified nodules.