Decomposition of some skarn-rock samples in neutral and basic molten potassium nitrate for the extraction and determination of iron

Five skarn-rock samples were heated with KNO3 and with a solution of 5% KOH in KNO3 for 2 h at 450 degrees C. The decomposed samples were cooled, dissolved in water and filtered. Iron was extracted from each residue as well as from the original samples by hot cone. HCl, and determined by atomic absorption spectroscopy These results were compared with the known (X-ray fluorescence) total iron content of the original samples. The amount of iron extracted with HCL from the skarn samples was 3-11% lower, while that extracted after heating with KNO3 alone was 2-4% lower, than the amount present according to the X-ray fluorescence results. However, the amount of iron extracted from the samples treated with a solution of KOH in KNO3 was comparable to that determined by X-ray fluorescence.