Inter-correlation of impurity trace elements in bloodstone rock: X-ray fluorescence mapping studies

Abstract

Studying impurities in rock systems is important to gaining an understanding on how the minerals themselves had been synthesized and how inhomogeneous colored patterns are formed. The present paper describes two-dimensional X-ray fluorescence (XRF) mapping of bloodstone and obtains the concentration distributions of Fe, Cu, Zn, Rb and Sr and intensity distribution of Si, Ti, Mn, Br, Y and Zr in a particular region of a sample from the integrated intensity of XRF spectra. The inter-correlation of impurity trace elements contained in rock systems is discussed quantitatively by employing the well-known Lachance-Traill algorithm. It was found that Ti and Mn are correlated to the major element Fe while Cu, Rb and Sr appear where low Fe concentration occurs and are related to the other major element Si. X-ray diffraction data suggests that Ti, Fe and Mn are identified as existing in the sample as a form of andradite. In conclusion, it has been suggested that bottle green is related to a Fe²⁺ or Cu compound, yellow and red are from the contribution of Fe₂O₃ or another Fe³⁺ compound, while black results from the contribution of Fe₃O₄.