Semi-quantitative ion microprobe mass analyses of mineral-rich particles from the upper freeport coal

An ion microprobe mass analyzer (IMMA) has been used to analyze semi-quantitatively mineral-rich coal particles from two separate facies of the Upper Freeport coal bed. Accuracy is estimated to be ∓ 20% for those elements making up more than 0.1 wt.% of the particles and ∓ 50% for elements making up less than 0.1 wt.%. Using IMMA data, we found statistically significant differences between the two samples for five (Fe, Ca, Mn, Li, Ce) of the 25 elements detected. For Li and Mn the differences between the mineral-rich particles within samples were similar to differences found between samples on a whole-coal basis. For Ca and Fe, the differences are attributed to different modes of occurrence, and for Ce, the differences are probably due to an irregular distribution of an inorganic phase. We conclude that the IMMA can be used to obtain semi-quantitative data that may provide insight into the distribution and mode of occurrence of some of the elements in coal.