Hydrogen speciation and trace element contents of igneous, hydrothermal and metamorphic quartz from Norway

Abstract Concentrations of a series of trace elements of 14 quartz samples from various geological settings (hydrothermal, igneous, metamorphic) in Norway were determined by LA-ICP-MS. FTIR spectroscopy was applied to the same quartz crystals in order to determine the H concentrations and the speciation of H in the quartz lattice. A refined hypothetical charge neutrality equation is suggested, where the atomic ratio of (Al 3+ + Fe 3+ + B 3+ ) to (P 5+ + H + + Li + + Na + + K + ) should correspond to 1 for natural quartz crystals. The determined concentrations of Al, Fe, B, P, Li, K and OH - species confirm approximately the charge neutrality equation. The high H/(Li+K+P) ion ratio of igneous quartz compared to hydrothermal and metamorphic quartz, suggests that igneous quartz preferentially incorporates H as OH- in lieu of Li, K and P. The results confirm that the FTIR absorption of the OH- band at 3595 cm -1 is attributed to structural B defects in the quartz lattice. The dominating H impurity in most of the quartz samples is, however, molecular H 2 O. The molecular H 2 O is presumably related to waterbearing micro pores and not to visible fluid inclusions, because the spectra were recorded from microscopically clear crystals.