New Experiment Illuminates Lithium Transport in Pegmatites

A team led by Christian Ronny Singer, Harald Behrens, Ingo Horn, Martin Oeser, Stefan Weyer, and François Holtz published a study that examines how lithium (Li) and boron (B) move through pegmatitic systems when fluids separate from molten rock ¹. The paper appears in volume 38 of the European Journal of Mineralogy, pages 497–518, and was released in 2026 ¹.

The experiment used a novel apparatus in which two independent melt reservoirs were linked solely by a fluid phase, mimicking the exsolution process that occurs during late‑stage pegmatite development ¹. By controlling temperature and pressure conditions representative of deep crustal settings, the researchers observed Li and B diffusion between the melts via the intervening fluid ¹.

Results showed that both Li and B were transported across the fluid barrier, although the transport rates were low ¹. More striking is the isotope behavior of lithium: the heavier ^7Li isotope became enriched in the fluid phase while the lighter ^6Li remained more concentrated in the surrounding melt ¹. This fractionation pattern indicates that fluid-mediated migration can selectively alter isotopic signatures during late‑stage mineralization.

The authors highlight that their experimental design offers a new tool for probing element transport under controlled conditions that closely resemble natural pegmatitic environments ¹