Synthetic and natural ammonium-bearing tourmaline

Wunder, Bernd; Berryman, Eleanor J.; Plessen, Birgit; Rhede, Dieter; Koch‐Müller, Monika; Heinrich, Wilhelm

doi:10.2138/am-2015-5055

Cited by 22 publications

(6 citation statements)

References 45 publications

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“…All three tourmalines show a small, but significant amount of Si at the octahedral Z site, which has already been observed for other synthetic tourmaline from high-pressure syntheses (Schreyer et al 2000;Wunder et al 2015).…”

Section: Emp and Sims Analysessupporting

confidence: 77%

Raman spectroscopic quantification of tetrahedral boron in synthetic aluminum-rich tourmaline

Kutzschbach

Wunder

Wannhoff

et al. 2021

American Mineralogist

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The Raman spectra of five [4]B-bearing tourmalines of different composition synthesized at 700 °C/4.0 GPa (including first-time synthesis of Na-Li-[4]B-tourmaline, Ca-Li-[4]B-tourmaline, and Ca-bearing ☐-[4]B-tourmaline) reveal a strong correlation between the tetrahedral boron content and the summed relative intensity of all OH-stretching bands between 3300–3430 cm–1. The band shift to low wavenumbers is explained by strong O3-H···O5 hydrogen bridge bonding. Applying the regression equation to natural [4]B-bearing tourmaline from the Koralpe (Austria) reproduces the EMPA-derived value perfectly [EMPA: 0.67(12) [4]B pfu vs. Raman: 0.66(13) [4]B pfu]. This demonstrates that Raman spectroscopy provides a fast and easy-to-use tool for the quantification of tetrahedral boron in tourma-line. The knowledge of the amount of tetrahedral boron in tourmaline has important implications for the better understanding and modeling of B-isotope fractionation between tourmaline and fluid/melt, widely used as a tracer of mass transfer processes.

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Section: Emp and Sims Analysessupporting

confidence: 77%

Raman spectroscopic quantification of tetrahedral boron in synthetic aluminum-rich tourmaline

Kutzschbach

Wunder

Wannhoff

et al. 2021

American Mineralogist

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“…9 mV signal intensity that would be visible on a mass scan. Additionally, mica also incorporates significant amount of NH 4 , in the same order of magnitude as that recorded in tourmaline (e.g., Boyd, 1997;Wunder et al, 2015), and its δ 7 Li is similar whether it is analyzed by MC-ICP-MS or LA-MC-ICPMS. Second, tourmaline is pyroelectric (e.g., Hawkins et al, 1995), and it may have an impact on Li ion behavior in the sample or the laser cell.…”

Section: Accepted Manuscriptmentioning

confidence: 75%

“…First, there may be a 14 N ++ spectral interference at mass 7. A recent paper demonstrated that tourmaline could incorporate significant amount of NH 4 (up to 500 µg/g in natural samples) in its crystal lattice (Wunder et al, 2015). However, such interference would create a ca.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

In situ lithium and boron isotope determinations in mica, pyroxene, and serpentine by LA-MC-ICP-MS

2015

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Boron and Li are light, incompatible elements that preferentially partition into the liquid phase, whether melt or aqueous fluid, and thus are useful for tracking fluid-related processes in rocks.Most of the Li isotopic data presently available on subduction-related rocks are from whole-rock analyses; and the B isotopic analyses of subduction material have been carried out either on whole-rocks or in-situ on an accessory phase, such as tourmaline. The new method presented here couples an ESI New Wave UP-193-FX ArF* (193 nm) excimer laser-ablation microscope with a Neptune Plus (Thermo Scientific) MC-ICP-MS aiming to measure both Li and B isotopes in situ with good spatial resolution (metamorphic minerals are commonly chemically zoned, and A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 whole-rock analyses lose this detail). The data thus obtained are compared with SIMS analyses on the same mineral samples for B, and with MC-ICP-MS analyses on whole-rock or mineral separates from the same sample for Li. Additionally, data acquired on tourmaline standards were compared to SIMS values. The results show that for B concentrations above 5 µg/g, the data obtained by LA-MC-ICP-MS and by SIMS are identical within error, for mica (phengitic muscovite), pyroxene (jadeite), serpentine (antigorite), and tourmaline. For Li concentrations above 10 µg/g, the data obtained by LA-MC-ICP-MS and by MC-ICP-MS are also identical, within error, for mica (phengitic muscovite), and pyroxene (jadeite). However, analyses of tourmaline standards have shown significant differences with reference values, so LA-MC-ICP-MS does not yet appear to be an appropriate method to analyze Li isotopes in tourmalines.Thus, LA-MC-ICP-MS is a suitable method to measure Li and B isotopes with good spatial resolution in major rock-forming silicates from subduction-related rocks where concentrations exceed 10 µg/g and 5 µg/g, respectively, with an error on individual measurements equal to or less than previously used methods, but obtainable in a significantly shorter amount of time. The external reproducibility is ± 2.88 to 3.31 ‰ for B and ± 1.50 to 1.75 for Li, which is lower than or equal to the variations encountered within a given chemically zoned sample (up to 10 ‰ of variation within a given natural sample).

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“…However, for ammonium in a crystal, ν 1 and ν 2 bands may appear in IR spectra due to decreased symmetry. FTIR spectroscopy is very sensitive to N-H vibrations and has been used to analyze NH 4 + in minerals in previous studies (e.g., Busigny et al 2003b;Watenphul et al, 2009Watenphul et al, , 2010Zhang et al 2010;Wunder et al 2015;Vennari et al 2016). The polarized and unpolarized IR spectra of NH 4 + in phengite at room temperature are shown in Figure 2.…”

Section: Ftir Spectra Of Nh 4 + In Phengite At Room Temperaturementioning

confidence: 99%

The fate of ammonium in phengite at high temperature

Yang

Busigny

Wang

et al. 2017

American Mineralogist

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Nitrogen (N) is the main component of the atmosphere and is largely considered as a volatile element. However, most researchers now agree that a significant amount of N, in the form of ammonium (NH 4 + ) substituting for K + in some K-bearing minerals such as clays, micas, and feldspars, can be transferred to the deep Earth through subduction. The fate of ammonium in those minerals during subduction is still poorly known but is likely controlled by temperature and pressure pathways. In an attempt to contribute to understanding the fate of N during high temperature processes, we carried out in situ high temperature IR and Raman spectra measurements to investigate the rate and mechanism of NH 4 + loss in phengite. We observed that a new OH band at 3425 cm -1 became prominent above 400 °C, and did not change with times during isothermal annealing at 500 and 700 °C. The N-H stretching band shifted to higher wavenumbers in the temperature interval from -150 to 20 °C, while linearly shifted to lower wavenumbers in the temperature interval from 20 to 500 °C and remained stable above 500 °C. The N-H bending band linearly shifted to lower wavenumbers in the temperature interval from -150 to 400 °C and remained stable. The K-O stretching 2 frequency decreased with increasing temperature to 600 °C, and then remained stable.These processes were reversible until dehydration and ammonium loss from phengite starting at 800 °C. The results suggest that (1) at low temperatures, ammonium is ordered and hydrogen bonding between ammonium and the framework evolves during cooling;(2) at high temperatures, the N-H interatomic distance of NH 4 + lengthens with increasing temperature until 500 °C. N-H bond subsequently no longer lengthens, accompanied by H transferring from N to neighboring O and forming a new OH band at 3425 cm -1 . At 800 °C, H + starts breaking from N and leaving others to form NH 3 and OH -. This study has implications for evaluating the extent to which these minerals can preserve information regarding nitrogen behavior during high temperature processes.

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Synthetic and natural ammonium-bearing tourmaline

Cited by 22 publications

References 45 publications

Raman spectroscopic quantification of tetrahedral boron in synthetic aluminum-rich tourmaline

Raman spectroscopic quantification of tetrahedral boron in synthetic aluminum-rich tourmaline

In situ lithium and boron isotope determinations in mica, pyroxene, and serpentine by LA-MC-ICP-MS

The fate of ammonium in phengite at high temperature

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