^1,2Laura E. Jenkins,¹Martin R. Lee,^1,3,4Luke Daly,⁵Ashley J. King,¹Peter Chung,¹Sammy Griffin,⁶Shijie Li
The American Mineralogist 110, 1238-1248 Link to Article [https://doi.org/10.2138/am-2024-9389]
¹School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, U.K.
²Diamond Light Source, Harwell Science and Innovation Campus, Fermi Avenue, Didcot OX11 0DE, U.K.
³Australian Centre for Microscopy and Microanalysis, University of Sydney, Camperdown, New South Wales 20250, Australia
⁴Department of Materials, University of Oxford, Oxford OX1 3PH, U.K.
⁵Planetary Materials Group, Natural History Museum, London SW7 5BD, U.K.
⁶Lunar and Planetary Science Research Center, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
Copyright: The Mineralogical Society of America

A hydrous Ca-Fe-rich silicate identified as hydroandradite was observed in the “Mighei-type” carbonaceous (CM) chondrite falls, Shidian and Kolang. This is the first report of hydroandradite occurring within meteorites. Hydroandradite forms through aqueous calc-silicate alteration under specific fluid conditions. Its presence within Shidian and Kolang has implications for interpreting alteration processes within the C-complex asteroid parent bodies of the CM chondrites. To better understand its occurrence, the meteoritic hydroandradite was studied with scanning electron microscopy, electron probe microanalysis, transmission electron microscopy, and Raman spectroscopy. It occurs in four petrographic contexts: layered, perovskite-associated, sulfide-associated, and spheroidal. Kolang has all four morphologies, while only the sulfide-associated occurs in Shidian. In Kolang, hydroandradite was likely produced by replacement of kamacite, Ti-bearing clinopyroxene in calcium- and aluminum-rich inclusions, and secondary magnetite in three distinct alteration events. The formation temperature of meteoritic hydroandradite was estimated to be 100–245 °C, based on the mineralogy of the lithologies within which it occurs as well as on its degree of hydration relative to synthetic and terrestrial hydroandradites. Because Kolang and Shidian are the only reported meteorites with hydroandradite to date, they may be from the same parent body.

¹Simon Stapperfend,²Donald B. Dingwell,²Kai-Uwe Hess,³Jennifer Sutherland,⁴Axel Müller,²Dirk Müller,²Michael Eitel,¹Julian Baasch,¹Stefan Linke,¹Enrico Stoll
American Mineralogist 110, 1171-1185 Open Access Link to Article [https://doi.org/10.2138/am-2023-9263]
¹Chair of Space Technology, Technische Universität Berlin, Marchstr. 12-14, 10587 Berlin,
Germany
²Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstraße 41/III, 80333 München, Germany
³Institut Laue-Langevin, 71 Av. des Martyrs, 38000 Grenoble, France
⁴OHB System AG, Manfred-Fuchs-Str. 1, 82234 Weßling, Germany
Copyright: The Mineralogical Society of America

In the context of evaluating lunar construction options, this study focuses on characterizing the viscosities and glass transition properties of lunar regolith simulants to support the development of additive manufacturing processes using molten regolith. Employing the modular TUBS lunar regolith simulant system, we measured the viscosities of different simulants through high-temperature experiments conducted between 1051 and 1490 °C using concentric cylinder viscometry in air. Additionally, differential scanning calorimetry (DSC) was utilized to evaluate the glass transition temperatures, which were in the range between 689 and 815 °C. The measured viscosity data were parameterized by the Vogel-Fulcher-Tammann (VFT) equation, which is adept at describing the viscosities and related properties of silicate liquids. The measured viscosities were compared with the predicted values of six viscosity models. The model by Sehlke and Whittington (2016) best predicts the viscosities of the tested lunar regolith simulants at superliquidus temperatures, and no model adequately predicts viscosities at the glass transition temperature, indicating a need for further research in this area. We infer that 3D printing technologies based on molten lunar regolith are, viscosity-wise, best constrained to highland regions. The reduced environment on the Moon influences the 3D printing process in a positive manner.