Paul Warren Hughes, William Frank Bradley, Herbert David Glass; Mineralogical analysis of carbonate rocks by X-ray diffraction. Journal of Sedimentary Research ; 30 (4): 619–A–622. doi: https://doi.org/10.2110/jsr.30.619a
Many minerals can be identified by X-ray diffraction from polished rock slices cut to fit in the sample holder of a diffractometer. Scanning from 20 degrees to 35 degrees 2theta gives the strong reflections of common minerals. Typical diffractometer patterns of limestone and dolomites are given.