Chemical speciation of trace titanium in Hamersley banded iron formations by X-ray fluorescence imaging and XANES analysis

Synchrotron radiation-induced X-ray fluorescence (SR-XRF) analysis was appl ied to examine the distributions and chemical forms of trace titanium in sa mples of banded iron formations (BIFs) from the Hamersley area of Western A ustralia. SR-XRF imaging and XANES (X-ray absorption near edge structure) a nalysis showed that titanium-enriched layers in the BIFs contained two type s of titanium compounds: Ti in silicate and titanium oxides. All the compou nds were in the tetravalent state. The difference between the two types of compounds may reflect different origins: i.e., the oxide phase may be preci pitated from the solutions and the silicate phase may come from elastic inp ut of terrigenous origin. SEM observation revealed peculiar spherical aggre gates that contained manganese carbonate, suggesting a possible relation to biological activity.