Identify the host phase of sodium in cometary matter

Identify the mineral or chemical host phase of sodium in cometary matter, including the possible roles of sodium sulfide and sodium-bearing GEMS-like phases.

Background

The paper reports that UCAMMs are enriched in sodium and that sodium-rich nanophases occur within type II organic matter. In UCAMM DC06-18, sodium enrichment is sometimes correlated with nitrogen enrichment near GEMS-like mineral phases, while a phase with a composition close to Na₂S was observed in UCAMM DC16-309.

Determining the host phase of sodium is relevant to interpreting the composition of cometary dust and to evaluating whether Na₂S combined with ammonium salts can reproduce the reflectance spectrum of comet 67P/Churyumov–Gerasimenko.