¹Caroline AVRIL,¹Valérie MALAVERGNE,²Eric D. VAN HULLEBUSCH,³Fabrice BRUNET,²Stephan BORENSZTAJN,⁴Jérôme LABANOWSKI,⁵Louis HENNET,⁶François GUYOT
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13641]
¹Laboratoire Géomatériaux et Environnement, Université Gustave Eiffel, EA 4508, UPEM, 5 boulevard Descartes, 77454 Marne‐la‐Vallée, Cedex 2, France
²Institut de physique du globe de Paris, CNRS, Université de Paris, F‐75005 Paris, France
³ISTerre, CNRS—Univ. Grenoble Alpes, Maison des Géosciences, BP 53, 38041 Grenoble Cedex 9, France
⁴Laboratoire de Chimie et Microbiologie de l’Eau, UMR CNRS 6008, Université de Poitiers, 40 avenue du recteur Pineau, 86022 Poitiers, France
⁵Conditions Extrêmes et Matériaux: Haute Température et Irradiation, UPR 3079 CNRS et université d’Orléans, 1d avenue de la recherche scientifique, 45071 Orléans Cedex 2, France
⁶Muséum National d’Histoire Naturelle, Sorbonne Universités, IMPMC UMR 7590 CNRS, 61 rue Buffon, 75005 Paris, France
Published by arrangement with John Wiley & Sons

Understanding the transformations of highly reduced enstatite chondrites (EC) in terrestrial environments, even on very short timescales, is important to make the best use of the cosmochemical and mineralogical information carried by these extraterrestrial rocks. Analogs of EC meteorites were synthesized at high pressure and high temperature. Then, their aqueous alterations, either abiotic or in the presence of the bacteria Acidithiobacillus ferrooxidans or Acidithiobacillus thiooxidans, were studied under air, at pH ~2, 20 °C, and atmospheric pressure. They stayed in shaken batch reactors for 15 days. Reference experiments were carried out separately by altering only one mineral phase among those composing the synthetic EC (i.e., sulfides: troilite or Mg‐Ca‐rich sulfides, enstatite, and Fe70Si30). Composition of the alteration aqueous media and microstructures of the weathered solids were monitored by inductively coupled plasma atomic emission spectroscopy and by scanning electron microscopy, respectively. Alteration sequence of the different mineral components of the synthetic EC was found to occur in the following order: magnesium‐calcium sulfides > troilite > iron‐silicon metallic phase > enstatite regardless of the presence or absence of the microorganisms. Such small biological effects might be due to the fact that the alteration conditions are far from biologically optimal, which is likely the case in most natural environments. The exposed surfaces of an EC meteorite falling on Earth in a wet and acidic environment could lose within a few hours their Ca‐ and Mg‐rich sulfides (oldhamite and niningerite). Then, in <1 week, troilite and kamacite could be altered. In a wet and acidic environment, only the enstatite would remain intact and would weather on a much slower geological timescale.

¹R. P. Lozano,²J. A. Sánchez,¹R. González‐Laguna,³T. Martín‐Crespo
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13645]
¹Museo Geominero, Instituto Geológico y Minero de España, C/Ríos Rosas 23, Madrid, 28003 Spain
²C/Rio Añamaza 4, 29620 Torremolinos, Málaga, Spain
³Departamento de Biología y Geología, Física y Química Inorgánica, ESCET, Universidad Rey Juan Carlos, C/Tulipán s/n, Móstoles, 28933 Madrid, Spain
Published by arrangement with John Wiley & Sons

Colomera is the Spanish meteorite (IIE) that has aroused the greatest interest among the international scientific community. Until now, the story of the find was only partially known and certain data are incorrect. The amazing journey of this meteorite has been recounted in this work. It reveals unpublished information derived from local archives, and testimonies from the descendants of the family that found the meteorite in 1913, and from the inhabitants of Colomera (Granada, Spain). We also document the story after its discovery, which culminated in a 2015 court ruling demanding the return of the largest part the mass (120.34 kg) to the heirs of the Spanish family that discovered the meteorite. Some of the material initially extracted in Spain (305 g) is currently housed in the Natural History Museum (121.3 g; London, UK). Nine kilograms of fragments remains in the United States after returning the meteorite to Spain in 1969. Of these, we have only located slightly more than 4 kg in several American institutions. Recently, 235 g has been returned to Spain: two fragments in private collections and two fragments in the Museo Geominero, Spanish Geological and Mining Institute (Spanish acronym: IGME).