Manganese incorporation in synthetic hercynite

Geoffrey Bromiley, G. Diego Gatta, T. Stokes

Research output: Contribution to journalArticlepeer-review


Manganese incorporation in synthetic hercynite, and partitioning between hercynite and silicate melt synthesized at 1.0 GPa, 1250°C, and at an f O2 buffered by Fe–FeO, has been studied by X-ray absorption spectroscopy and single-crystal X-ray structure refinement. Spectra indicate the presence of both Mn2+ and Mn3+ (and possibly also Mn4+) in synthetic hercynite and partitioning of Mn2+ into the melt phase, and Mn3+ into hercynite, respectively, under run conditions. X-ray refinement is consistent with partial disorder of Fe and Al across tetrahedral and octahedral sites. A higher than expected degree of Fe-Al disorder in the Mn-bearing hercynite can be explained by preferential incorporation of Mn2+ onto the tetrahedral site, and indicates that Fe-Al disorder in pure, stoichiometric hercynite cannot necessarily be used to determine closure temperatures in natural spinel. However, partitioning of Mn2+ and Mn3+ between melt and hercynite suggests that Mn incorporation in hercynite could be used as a measure of f O2 conditions in magmas during spinel crystallization.
Original languageEnglish
Pages (from-to)635-647
Number of pages13
JournalMineralogical Magazine
Issue number3
Publication statusPublished - 1 Jun 2015


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