I have a powder sample which its color is near to the color of ferrous sulfate. I want to determine qualitatively if there is any ferrous sulfate in that.
EDX might be difficult. A common EDX requires a minimum concentration of about 5% to detect it. It depends therefor on your Sulfur-concentration whether you can detect it or not. RFA (xray fluorecent analysis)or AAS (atom adsorbtion analysis) might be the more precise method.