Ausson





AUSSON – To my meteorite friends

Ordinary chondrite (L5, S2 or S3)
Fell, 9 December 1858, 7:30 hrs; 50 kg, 2 stones

History:
The Ausson meteorite took place on December 9, 1858 in Ausson, France. Two stones were found but both stones were heavily damaged by the inhabitants. The Toulouse Academy of Science sent three scientists that could bring back only fragments, including one of 800 grams. For the place of find : one stone fell on a house near the church of Clarac (the stone weighed initially 8 to 10 kg). The other fell in a field near Montréjeau (exact place is unknown) and the stone weighed initially 40 to 45 kg

The largest masses have been housed at the Museum d’Histoire Naturelle in Paris [1.0828 kg, 799.7 g, and 14 smaller specimens in 2017]. A number of masses, now in the 1.1 kg to 100 g range, were distributed to the corresponding Museum d’Histoire Naturelle in Toulouse and elsewhere.

Specimen:
This is a crusted fragment weighting 150 grams with attached handwritten museum label on the specimen. Specimen comes with 4 museum labels and one hand written letter. Three labels are from The Mineralogical Museum of the University, Copenhagen and one is from Mr Paul Graves.

Translation of the hand written letter:
“Aerolite of Montrejeau (Haute-Garonne) fallen on December 9, 1858.
See in the Proceedings of the Academy of Sciences of Paris the memory and analysis, by M.m. Leymerie, Filhol, Chancel, Moitessier, Damour, & c.
fragment of 150gr, 079.
density, according to M. Chancel, 3.58.”

This piece was exchanged to The Mineralogical Museum of the University, Copenhagen from Mr Paul Gervais when he was a Professor of Zoology in the Faculty of Sciences of Montpellier (1847-1865). This can been seen from Copenhagen catalogue from 1861, when this piece was already in Copenhagen collection. Paul Gervais worked as a Professor of Zoology in the Faculty of Sciences of Montpellier (1847-1865) at the time of the meteorite fall. Montpellier is not very far from Toulouse so there had been some relation with Toulouse Academy of Sciences. There is a proof that Leymerie who was one of the Professors in Toulouse who analyzed the meteorite knew Gervais, as Leymerie sent a fossil to him, when Gervais was at the Museum of Paris. So this tells that there was some connection between Toulouse and Montpellier.
Specimen is listed in the collection catalogue of The Mineralogical Museum of the University, Copenhagen and was later exchanged from the museum by a French meteorite hunter and collector Luc Labanne.
Thanks to Pierre-Marie Pele and Luc Labanne for help in solving the history of this meteorite specimen!

Then the piece was exchange to The Mineralogical Museum of the University, Copenhagen. Piece is listed in the

About Paul Gervais: Zoologist and paleontologist. – Doctor of Science (1844). – Doctor of Medicine (1856). – Professor of Zoology, then anatomy compared to the Faculty of Sciences of Montpellier (1847-1865). – Holder of the chair of zoology at the Sorbonne (1865-1868). – Holder of the chair of comparative anatomy at the National Museum of Natural History (from 1868). – Member of the Institute, Academy of Sciences (elected in 1874)
Montpellier is not very far from Toulouse so there had been some relation with Toulouse Academy of Sciences. There is a proof that they know each other as Leymerie sent to him a fossil ,when Gervais was at the Museum of Paris.

Bulk iron contents (23.8 wt%Fe) along with olivine (Fa~24) and low Ca-orthopyroxene (Fs~22) composition are characteristic of the L-chondrite geochemical group. Mineralogically the meteorite consists primarily of silicates (dominant olivine and orthopyroxene along with minor and somewhat variable plagioclase). Silicates are accompanied by lesser amounts of troilite and Fe-Ni metal (kamacite, taenite). Accessory chromite, apatite, copper, and diopsidic pyroxene have also been reported. The presence of plessite and variable plagioclase is consistent with significant post-metamorphic shock events in the pre-terrestrial meteoroid. The Catalogue of Meteorites lists Ausson as a shock level S2 meteorite, but a recent study using magnetic hysteresis suggests that an S3 shock level is more appropriate. However, it should be noted that Ausson specimens are somewhat inhomogeneous and may have been differentially shocked before final accretion onto the eventual earth-impacting meteoroid.

A formational age for the original parent body during the ~4.5 Ga formational epoch seems well established. A 3.17 Ga Pb,Th-He gas release age suggests at least one significant impact during the intervening eons. However, close inspection of a relatively long cosmic ray exposure age (very roughly, 70 Ma) suggests a complex exposure history during the preterrestrial meteoroid’s final period before earth-encounter, perhaps due to multiple impacts during the last few millions of years.

The L-group of ordinary chondrites (relatively low in total iron) are the largest group of classified witnessed meteorite falls and account for ~45% of the well-classified meteorite falls. The L5 petrologic type account for ~ 20% of the group. Ausson is the 8th most massive of the 82 meteorite falls currently classified as exactly ‘L5’ chondrites at the Meteoritical Bulletin Database (June 2017).

The largest masses have been housed at the Museum d’Histoire Naturelle in Paris [1.0828 kg, 799.7 g, and 14 smaller specimens in 2017]. A number of masses, now in the 1.1 kg to 100 g range, were distributed to the corresponding Museum d’Histoire Naturelle in Toulouse and elsewhere.

The Ausson meteorite took place on December 9, 1858 in Ausson, France. Two stones were found , one in Ausson and the other in Clarac. The first stone was shared among the locals and more than likely lost to science.

The second stone hit a wooden house, and most, if not all of the Ausson currently on the market came from this stone.

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