Tintigny: A Polymict Eucrite from Belgium

In February 1971, a meteorite fell on the roof of a barn belonging to Mr. E. Schmitz in Tintigny, a village in southern Belgium. Upon its recovery, its meteoritic origin was confirmed by the schoolteacher, Mr. A. Rossignon who then looked after the sample. In 2017, for the first time, the meteorite was given to specialists for a detailed examina-tion and classification. We used various analytical techniques to characterize its mineralogy, elemental, and isotopic composition. Based on the obtained data, we classified it as a polymict eucrite, a meteorite originating from 4 Vesta, and named it Tintigny [1]. Tintigny is partly covered by shiny black fusion crust. Its interior mainly exhibits a light grey color and shows a brecciated texture composed of a fine-grained matrix, hosting darker crystals and cm-sized dark grey clasts. Under the microscope, a brecciated sub-ophitic basaltic texture mainly composed of plagioclase/maskelynite and clinopy-roxene is dominant. In addition to the dominant sub-ophitic texture, at least three distinct textures exposed in clasts are observable. At least two generations of shock effects (such as fractures), are present in the sample: those limited to clasts and large crystals, and those that crosscut both the large grains and the matrix. The accessory minerals include troilite, ilmenite, chromite, FeNi metal, and silica. Mineral chemistry calculations of pyroxene end-members show ranges from 8.5 to 60.7 mol% for enstatite, 30.1–70.0 mol% for ferrosilite, and 2.6–38.4 mol% for wollastonite. Based on these values, most pyroxenes in Tintigny are pigeonite and augite [2]. The Fe/Mn ratios of pyroxenes range from 27.1 to 39.3, with the highest ratio observed in pyroxene from the symplectitic clast. Fe/Mn and Fe/Mg ratios in low-Ca pyroxene (Wo<10) are 30.2±4.4 and 0.8±0.3, respectively. These ratios in high-Ca pyroxene (n=8) are 34.3±3.7 for Fe/Mn and 2.6±2.4 for Fe/Mg. The average pyroxene Fe/Mn ratio for all pyroxene is 32.5±4.4 (SD, n=14). Fe/Mg ranges from 0.6 to 8.2, with an average value of 1.8±2.0 (SD, n±14). Considering pyroxene Fe/Mn ranges of 40±11, 62±18, 32±6, and 30±2 for basaltic rocks from the Earth, Moon, Mars, and 4 Vesta (eucrites), respectively, and based on our data, particularly those of low-Ca py-roxene, Tintigny falls in the range of basaltic eucrites [3]. The bulk rock Fe/Mn and Fe/Mg ratios of Tintigny are 33.9 and 3.1, respectively. These values overlap with those measured for howardite-eucrite-diogenite (HED) and martian meteorites [4]. With a Ga/Al ratio of 4.17×10-5, Tintigny falls within the range of those of eucrites. Using the CI-normalized elemental concentration, we can see strong simi-larities between Tintigny and noncumulate eucrites, which is also reflected based on the abundance of TiO2 (0.63) and FeO/MgO ratio (2.66) in Tintigny. The bulk oxygen isotopic composition of Tintigny, as determined by laser fluorination, is also consistent with it being an HED (δ17O=1.72±0.04 ‰; δ18O=3.76±0.08‰; Δ17O=-0.25±0.01 ‰ (n=2, errors 2SD)), with a composition that plots close to the Eucrite Fractionation Line [5]. Based on the Meteoritical Bulletin Database, only 70 HED falls have been reported so far. Including Tintigny, only 39 eucrite falls are known to date, 11 of them occurred in Europe, with Tintigny being the only one from Belgium. In addition to the scientific importance of studying a eucrite fall like Tintigny, we emphasize the significance of the discovery of a historical meteorite fall by drawing attention to national scientific heritage that must be properly un-derstood and safeguarded for generations of scientists, scholars, and amateurs to come. Nowadays, together with four other meteorites from Belgium (Hautes Fagnes LL5, Lesves L6, St. Denis Westrem L6, and Tourinnes-la-Grosse L6), the Tintigny achondrite is exhibited in the meteorite gallery of the Institute of Nat-ural Sciences in Brussels and is open to the public for visits.

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