gems, advanced testing, analytical testing, chemistry, PIXE, PIGE, tourmaline

Simultaneous and accurate measurements of boron and lithium relative amounts and boron isotopic ratios were performed in tourmaline samples by nuclear microprobe analysis (NMA), using the (p, p′ γ) reactions on ¹⁰B, ¹¹B, and ⁷Li and with a proton microbeam at an energy of 3.3 MeV and an average current density of 10–15 μA/cm². We detail the experimental procedure as well as the calibration of the method using several standard matrices. The analytical capability for elemental and isotopic analyses of lithium and boron in tourmaline minerals by NMA is discussed.