Trace elements in magnetite from Kiruna, northern Sweden, as determined by LA-ICP-MS

Abstract

Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) has been used to determine the concentrations of 17 trace elements (V, Mn, Cu, Zn, Rb, Sr, Mo, Ag, Cd, Sb, Ba, Ce, Tl, Pb, B, Th, and U) in magnetite from the Kiirunavaara iron deposit in northern Sweden. Magnetite grains were sampled from four different parts of the concentrating plant. An attempt was made to investigate if there are any concentration differences between the surface layer and interior layers in magnetite grains, using a two-stage soft ablation procedure. Possible non-representative sampling due to fractionation, was evaluated by using a polished in-house calibration standard. The two-stage ablation showed no significant differences between the first and second layer, in terms of elemental compositions. Concentrations of V (up to 2300 μg/g) and Mn (up to 7850 μg/g) are the most abundant trace elements encountered. Cu, Zn, and Pb are among the less common trace elements in magnetite. The conversion of intensity signals of the elements to concentration values mg/g was achieved by using a polished in-house magnetite standard and Fe for internal standardization.