EGU25-17874, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-17874
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Spectral characterization of lab-made silicate glasses as analogues for Mercury: influence of grain size and chemical composition.
Alessandro Pisello1, Maximiliano Fastelli1, Enrico Scricciolo1, Marco Baroni1, Alessandro Musu2, Paola Comodi1, and Diego Perugini1
Alessandro Pisello et al.
  • 1Università degli Studi di Perugia, Dipartimento di Fisica e Geologia, Perugia, Italy (alessandropisello@gmail.com)
  • 2Department of Lithospheric Research, University of Vienna, UZA2, Josef-Holaubek-Platz 2, 1090 Vienna, Austria.

Volcanic and magmatic processes have played a significant role in shaping Mercury’s surface and contributing to its mineral diversity. Areas such as smooth plains, which cover 27% of the planet, are thought to have formed from effusive volcanic events. Explosive volcanism is also suggested by the presence of depressions surrounded by high-reflectance halos, calderas, and vents linked to impact structures or faults. The BepiColombo mission, a collaboration between ESA and JAXA, was launched in 2018 to explore Mercury. It consists of two orbiters, MIO (JAXA) and MPO (ESA), with a focus on studying the planet's interior, surface, exosphere, and magnetosphere. The MPO carries instruments such as SIMBIO-SYS and MERTIS, which are designed to acquire spectral data.

Interpreting planetary surface data often requires understanding complex factors like mineral composition, elemental abundance, temperature, and particle size. This study investigates the mid-infrared (MIR) spectral response of silicate glasses with a range of grain sizes and chemical compositions, aiming to build a database to support future spectral analyses of Mercury’s surface, where volcaniclastic materials are expected to be abundant.

Three compositions resembling the Northern Volcanic Plains (NVP) on Mercury were prepared: NVP, NVP_Na, and NVP_Mg, each with varying amounts of Na and Mg. These compositions were created by melting pure oxides at 1400°C, then crushing the resulting glass into powder and re-melting it to ensure homogeneity. The glass was sieved into various grain size fractions, with some samples mixed to create new samples with Gaussian-like distributions to explore how fine-grained fractions affect spectral responses, particularly in relation to volcanic ash.

Spectroscopic analysis was performed using a Bruker Invenio-X FT-IR spectrometer. The VNIR spectra (400-2000 nm) showed typical features of silicate glasses, with an absorption peak at around 1100 nm and a weaker one at 1900 nm, related to Fe-O bonds. The slope of the spectra did not vary much with increasing grain size in NVP samples, but there was a noticeable increase in the NIR slope (1200-1800 nm) for NVP_Na and NVP_Mg.

In the MIR region (7-14 µm), the spectra revealed a correlation between the shape of the spectra and the chemical and granulometric characteristics of the samples. A local maximum at 10000 nm was observed for all spectra, associated with tetrahedral silicate units, and the NVP_Mg spectra showed distinct features due to the network-modifying role of Mg. The spectra also exhibited the Christiansen Feature at around 8 µm, a diagnostic feature for igneous products, and a transparency feature around 12 µm, which appeared in spectra of finer-grained samples.

These spectra will be made available on the SSDC-ASI portal and will be crucial for interpreting data from the BepiColombo mission, particularly from SIMBIO-SYS and MERTIS. This research will help in identifying potential unknown igneous materials on Mercury’s surface.

How to cite: Pisello, A., Fastelli, M., Scricciolo, E., Baroni, M., Musu, A., Comodi, P., and Perugini, D.: Spectral characterization of lab-made silicate glasses as analogues for Mercury: influence of grain size and chemical composition., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17874, https://doi.org/10.5194/egusphere-egu25-17874, 2025.