The easiest way, at least for me, is to use Rietveld's diffraction data processing method. There are many software resources for this purpose, some of them free. I use Topas now, which is commercial.

In such a simple case, such as the calcite/aragonite ratio, other methods of quantification such as the RIR or external calibration curve could also be used.

You can find the quantitative Rietveld XRD method described, applied and the data (calcite-low Mg, calcite-high Mg + aragonite) interpreted along a coastal profile:

DILL, H.G., UFER, K., BORNEMANN, A., TECHMER, A. , and  BUZATU, A. (2019) From the strand plain to the reef:  A sedimentological–geomorphological study of a Holocene coast affected by mud diapirism (ArchipélagoRosario- Barú, Colombia).-Marine Geology 415:  (in  print)

Available at the RG server for download on request

I agree with Dalibor Matýsek Sir. Yes, Topas now only available in commercial mode. But as you are in IIT you can try for that, if not then try Match 2 software.

You can also do it with MAUD software which also uses Rietveld method and it is noncomercial.

Hi Dear Jeet Majumder

I prefer to use MAUD software for quantitative analysis (Fase fraction, strain, Crystallite size, Dislocation density, etc) because It is one of the strongest software and easy to use.

Also, it is free. You can download it from this site :

http://maud.radiographema.eu/

Good luck