AbstractHematite ore fractions in the form of circulating slurries of various solids content were analyzed for iron and silicon, their principal metallic constituents, to determine the relationships and factors significant to such analyses. Radioisotopes were used to excite the characteristic radiations which were measured nondispersively. Counts were also taken for the exciting radiations.The measured intensities for Fe Kα and Si Kα were corrected by backscatter and absorption factors derived by the comparison of counts from the slurries to those from water. Regression lines were used to convert all counts to a 40% solid basis.The iron content of the ore fractions was determined with a standard error of less than 2%. The determination of silicon was not satisfactory at low concentrations because all components of the slurries absorb Si Kα strong