¹Maximilian P. Reitze, ¹Iris Weber, ¹Andreas Morlok, ¹Harald Hiesinger, ¹Johannes Benkhoff, ¹Jan Hendrik Pasckert, ¹Nico Schmedemann, ¹Thomas Heyer, ²Solmaz Adeli
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2026.117073]
¹Institut für Planetologie, Universität Münster, Wilhelm-Klemm Str. 10, Münster, 48149, Germany
²Deutsches Zentrum für Luft- und Raumfahrt (DLR, Rutherfordstr. 2, Berlin, 12489, Germany
Copyright Elsevier

In this work, we propose a new potential mechanism for the formation of the so-called hollows on Mercury, hypothesizing that they are composed of carbonatites—volcanic rocks that are exceedingly rare on Earth. To evaluate this hypothesis, mid-infrared spectroscopic measurements were performed on a rare, unaltered terrestrial carbonatite sample from Mount Ol Doinyo Lengai, Tanzania, composed primarily of the carbonate minerals nyerereite and gregoryite. For comparison, spectra of several common terrestrial carbonate minerals were also acquired. The collected spectra display characteristic features of carbonate minerals. Our analysis suggests that carbonatite rocks should be taken into account for several physical properties required for the formation of hollows on Mercury’s surface. These include appropriate thermal stability, chemical composition, and surface coloration. In particular, the eruption temperatures of terrestrial carbonatite lavas are less than 100 °C below Mercury’s estimated daytime surface temperatures. This thermal similarity makes the measured spectra relevant for the MERTIS instrument onboard the BepiColombo spacecraft, which will investigate Mercury’s surface mineralogy in near future.