7 research outputs found
Byne's decay : calcium salt efflorescence on micropalaeontology collections
L'apparition d'efflorescences cristallines sur des objets calcaires stockĂ©s dans des environnements polluĂ©s, communĂ©ment appelĂ©e "dĂ©gradation de Byne", rĂ©sulte de l'Ă©mission de composĂ©s organiques volatils (COV) acides par les matĂ©riaux de stockage. Ces acides rĂ©agissent avec le carbonate de calcium en formant des sels organiques de calcium, dont des acĂ©tates et des sels mixtes acĂ©tate-formiate, qui provoquent une dĂ©tĂ©rioration irrĂ©versible du substrat. Jusqu'Ă prĂ©sent, seuls des objets macroscopiques subissant la dĂ©gradation de Byne avaient Ă©tĂ© dĂ©crits dans la littĂ©rature.Ce travail vise Ă comprendre comment la dĂ©gradation de Byne peut aussi affecter des spĂ©cimens calcaires microscopiques prĂ©sents dans les collections de micropalĂ©ontologie. Il a Ă©tĂ© initiĂ© par la numĂ©risation de la collection de foraminifĂšres d'Alcide d'Orbigny (1802-1857), conservĂ©e au MusĂ©um national d'Histoire naturelle (MNHN), qui a rĂ©vĂ©lĂ© des dommages importants liĂ©s Ă la prĂ©sence d'efflorescences salines.Un constat d'Ă©tat a Ă©tĂ© menĂ© sur l'ensemble de la collection d'Orbigny (plus de 3600 spĂ©cimens), mettant en Ă©vidence que les altĂ©rations, Ă la fois anciennes et Ă©volutives, sont influencĂ©es par la cristallinitĂ© des tests et l'origine des lieux de prĂ©lĂšvement des foraminifĂšres. Des collections voisines ont Ă©tĂ© examinĂ©es Ă titre comparatif et des recherches en archives ont permis de retracer l'histoire de la collection depuis son entrĂ©e au MNHN. Elles mettent en Ă©vidence de nombreux dĂ©mĂ©nagements et des accidents tels que la crue de la Seine de 1910, qui expliquerait l'humiditĂ© particuliĂšrement Ă©levĂ©e Ă l'intĂ©rieur des tubes oĂč sont conservĂ©s les foraminifĂšres. Des variations importantes de tempĂ©rature, combinĂ©es Ă la prĂ©sence de matĂ©riaux Ă©metteurs de COV introduits Ă la fin du XIXe siĂšcle dans le montage des spĂ©cimens, sont ainsi Ă l'origine de la pollution acide et de la prolifĂ©ration des sels.ParallĂšlement Ă cela, une procĂ©dure de vieillissement artificiel a Ă©tĂ© Ă©laborĂ©e pour reproduire la dĂ©gradation de Byne sur des foraminifĂšres sains. Les produits de dĂ©gradation formĂ©s sur les spĂ©cimens vieillis, ainsi que sur une sĂ©lection reprĂ©sentative de spĂ©cimens historiques, ont Ă©tĂ© analysĂ©s de maniĂšre non invasive et sans contact par spectroscopie micro-Raman et par diffraction des rayons X sur rayonnement synchrotron. Ces analyses ont mis en Ă©vidence des phases minĂ©ralogiques diffĂ©rentes de celles observĂ©es dans la littĂ©rature sur les collections macroscopiques. Ce sont ainsi des formiates de calcium qui prĂ©dominent, et tout particuliĂšrement le polymorphe tĂ©tragonal [ÎČ-Ca(HCOO)2] connu pour ĂȘtre instable lorsqu'il est synthĂ©tisĂ© en laboratoire. Aucun acĂ©tate ou sel mixte de calcium n'a pu ĂȘtre identifiĂ© sur les foraminifĂšres de la collection d'Orbigny. Les vieillissements montrent que l'humiditĂ© relative et la taille des spĂ©cimens jouent un rĂŽle primordial dans la formation des sels : des conditions humides favorisent la cristallisation du formiate de calcium sur le spĂ©cimen, tandis que l'acĂ©tate, trĂšs hygroscopique, est sujet aux cycles de dĂ©liquescence-cristallisation qui le conduisent Ă se disperser autour de l'Ă©chantillon lorsque celui-ci est de trĂšs petite taille.Enfin, pour mieux comprendre la prĂ©dominance du formiate de calcium [ÎČ-Ca(HCOO)2], diffĂ©rentes solutions de formiate de calcium ont Ă©tĂ© laissĂ©es Ă Ă©vaporer et placĂ©es dans des environnements Ă humiditĂ© variĂ©e afin d'Ă©tudier la transformation vers la phase stable [α-Ca(HCOO)2]. L'analyse semi-quantitative des produits montre que la prĂ©sence d'ions tels que ceux trouvĂ©s dans les coquilles de foraminifĂšres (Mg2+, Sr2+...) favorise la formation de la phase mĂ©tastable, et ralentit la transition ÎČ-->α.Ce travail montre que la nature des sels formĂ©s par la dĂ©gradation de Byne n'est pas seulement tributaire des COV prĂ©sents mais dĂ©pend aussi de la taille des spĂ©cimens, leur composition, la cristallisation de leur test et des cycles d'humiditĂ© et de tempĂ©rature auxquels ils ont Ă©tĂ© soumis.The appearance of crystalline efflorescence on calcareous objects stored in polluted environments is commonly referred to as "Byne's decay". It results from the emission of acidic volatile organic compounds (VOCs) from storage materials, which react with calcium carbonate to form organic calcium salts. This includes acetates and mixed acetate-formate salts that cause irreversible deterioration of the substrate. Until now, only macroscopic objects undergoing Byne's decay had been reported in the literature.This work focuses on how Byne's decay can also affect microscopic calcareous specimens from micropaleontology collections. It was initiated by the digitization of the foraminifera collection of Alcide d'Orbigny (1802-1857), housed at the MusĂ©um national d'Histoire naturelle (MNHN), which revealed significant damage due to the presence of saline efflorescences.A condition report was carried out on the whole of the d'Orbigny collection (more than 3600 specimens), highlighting that the alterations, both ancient and evolutionary, are influenced by the crystallinity of the tests and the origin of the places where the foraminifera were collected. Similar collections closely located were examined for comparison and archival research was conducted to trace the material history of the collection since its entry into the MNHN. They highlight several moves and accidents such as the flooding of the Seine in 1910, which would explain the particularly high levels of humidity inside the tubes where the foraminifera are kept. Significant variations in temperature, combined with the presence of VOC-emitting materials introduced at the end of the 19th century in the assembly of the specimens, are thus at the origin of the acid pollution and the proliferation of salts.At the same time, an artificial aging procedure was developed to reproduce Byne's decay on unaltered specimens. The degradation products formed on the aged specimens, as well as on a representative selection of historical ones, were analysed non-invasively and without contact by using micro-Raman spectroscopy and synchrotron X-ray diffraction. These analyses revealed mineralogical phases different from those observed in the literature on macroscopic collections. Thus, calcium formates and especially the tetragonal polymorphic phase [ÎČ-Ca(HCOO)2] known to be unstable when synthesized in laboratory conditions, predominate. No calcium acetate or mixed salt could be identified on d'Orbigny's foraminifera. Aging shows that the relative humidity and the size of the specimens play a primordial role in the formation of the salts: humid conditions favour the crystallization of calcium formate directly on the specimen, while acetate, very hygroscopic, is subject to deliquescence-crystallization cycles that lead to its redispersion around micrometer-scale specimens.Finally, to better understand the predominance of calcium formate [ÎČ-Ca(HCOO)2], different calcium formate solutions were left to evaporate and placed in environments with different humidity to study the transformation towards the stable phase [α-Ca(HCOO)2]. Semi-quantitative analysis of the products shows that the presence of ions such as those found in foraminiferal shells (Mg2+, Sr2+âŠ) favours the formation of the metastable phase and slows down the transition ÎČ-->α.This work shows that the nature of the salts formed by Byne's decay is not only dependent on the VOCs present, but also on the size of the specimens, their composition, their test crystallization, and the moisture and temperature cycles to which they were exposed
La dégradation de Byne : efflorescences de sels de calcium sur les collections de micropaléontologie
The appearance of crystalline efflorescence on limestone objects stored in polluted environments, commonly referred to as "Byneâs decay", results from the emission of acidic volatile organic compounds (VOCs) from storage materials. These acids react with calcium carbonate to form organic calcium salts, including acetates and mixed acetate-formate salts, which cause irreversible deterioration of the substrate. Until now, only macroscopic objects undergoing Byne degradation had been reported in the literature. This work thus focuses on how Byneâs decay can also affect microscopic limestone specimens in micropaleontology collections. It was initiated by the digitization of the foraminifera collection of Alcide d'Orbigny (1802-1857), preserved at the MusĂ©um national d'Histoire naturelle (MNHN), which revealed significant damage due to the presence of saline efflorescences. A condition report was carried out on the whole of the d'Orbigny collection (more than 3600 specimens), highlighting that the alterations, both ancient and evolutionary, are influenced by the crystallinity of the tests and the origin of the places where the foraminifera were collected. Similar collections were examined for comparison and archival research was conducted to trace the material history of the collection since its entry into the MNHN. They highlight wide variations in temperature and historical events such as the flooding of the Seine in 1910, which would explain the particularly high humidity levels inside the tubes where the foraminifera are kept. These variations in temperature and humidity, combined with the presence of VOC-emitting materials introduced at the end of the XIXth century into the specimensâ mounting, are at the origin of the acid pollution and proliferation of salts. At the same time, an artificial aging procedure was developed to reproduce Byneâs decay on healthy microspecimens. The degradation products formed on the aged specimens, as well as on a representative selection of historical specimens, were analysed non-invasively and without contact by micro-Raman spectroscopy and synchrotron X-ray diffraction. These analyses revealed mineralogical phases different from those observed in the literature on macroscopic collections. Thus, calcium formates and especially the ÎČ-polymorph of calcium formate, known to be unstable when synthesized in laboratory conditions, predominate. No calcium acetate or mixed salt could be identified on dâOrbigny's foraminifera. Aging shows that the relative humidity and the size of the specimens play a primordial role in the formation of the salts: humid conditions favour the crystallization of calcium formate directly on the specimen, while acetate, very hygroscopic, is subject to deliquescence-crystallization cycles that lead it to disperse around the specimen if this one is too small (typically at the micrometric scale). Finally, to better understand the predominance of the ÎČ-polymorph of calcium formate, different calcium formate solutions were left to evaporate and placed in environments with varying humidity to study the transformation ÎČα. Semi-quantitative analysis of the products shows that the presence of foreign ions such as those present in foraminiferal shells (Mg2+, Sr2+âŠ) favours the emergence of the ÎČ-polymorph, and slows its transition to the stable phase.This work shows that the nature of the salts formed by Byne degradation is not only dependent on the VOCs present, but also on the size of the specimens, their composition, their test crystallization, and the moisture and temperature cycles to which they were exposed.L'apparition d'efflorescences cristallines sur des objets calcaires stockĂ©s dans des environnements polluĂ©s, communĂ©ment appelĂ©e "dĂ©gradation de Byne", rĂ©sulte de l'Ă©mission de composĂ©s organiques volatils (COV) acides par les matĂ©riaux de stockage. Ces acides rĂ©agissent avec le carbonate de calcium en formant des sels organiques de calcium, dont des acĂ©tates et des sels mixtes acĂ©tate-formiate, qui provoquent une dĂ©tĂ©rioration irrĂ©versible du substrat. Jusqu'Ă prĂ©sent, seuls des objets macroscopiques subissant la dĂ©gradation de Byne avaient Ă©tĂ© rapportĂ©s dans la littĂ©rature. Ce travail porte ainsi sur la maniĂšre dont la dĂ©gradation de Byne peut aussi affecter des spĂ©cimens calcaires microscopiques prĂ©sents dans les collections de micropalĂ©ontologie. Il a Ă©tĂ© initiĂ© par la numĂ©risation de la collection de foraminifĂšres d'Alcide d'Orbigny (1802-1857), conservĂ©e au MusĂ©um national d'Histoire naturelle (MNHN), qui a rĂ©vĂ©lĂ© des dommages importants liĂ©s Ă la prĂ©sence dâefflorescences salines. Un constat dâĂ©tat a Ă©tĂ© menĂ© sur lâensemble de la collection dâOrbigny (plus de 3600 spĂ©cimens), mettant en Ă©vidence que les altĂ©rations, Ă la fois anciennes et Ă©volutives, sont influencĂ©es par la cristallinitĂ© des tests et lâorigine des lieux de prĂ©lĂšvement des foraminifĂšres. Des collections voisines ont Ă©tĂ© examinĂ©es Ă titre comparatif et des recherches en archives ont Ă©tĂ© menĂ©es pour retracer lâhistoire matĂ©rielle de la collection depuis son entrĂ©e au MNHN. Elles mettent en Ă©vidence de larges variations de tempĂ©rature et des Ă©vĂšnements historiques tels que la crue de la Seine de 1910, qui expliquerait les taux dâhumiditĂ© particuliĂšrement Ă©levĂ©s Ă l'intĂ©rieur des tubes oĂč sont conservĂ©s les foraminifĂšres. Ces variations de tempĂ©rature et dâhumiditĂ©, combinĂ©es Ă la prĂ©sence de matĂ©riaux Ă©metteurs de COV introduits Ă la fin du XIXe siĂšcle dans le montage des spĂ©cimens, sont Ă lâorigine de la pollution acide et de la prolifĂ©ration des sels. ParallĂšlement Ă cela, une procĂ©dure de vieillissement artificiel a Ă©tĂ© Ă©laborĂ©e pour reproduire la dĂ©gradation de Byne sur des microspĂ©cimens sains. Les produits de dĂ©gradation formĂ©s sur les spĂ©cimens vieillis, ainsi que sur une sĂ©lection reprĂ©sentative de spĂ©cimens historiques, ont Ă©tĂ© analysĂ©s de maniĂšre non invasive et sans contact par spectroscopie micro-Raman et par diffraction des rayons X sur ligne synchrotron. Ces analyses ont mis en Ă©vidence des phases minĂ©ralogiques diffĂ©rentes de celles observĂ©es dans la littĂ©rature sur les collections macroscopiques. Ce sont ainsi des formiates de calcium et tout particuliĂšrement le ÎČ-polymorphe du formate de calcium, connu pour ĂȘtre instable lorsqu'il est synthĂ©tisĂ© en laboratoire, qui prĂ©dominent. Aucun acĂ©tate ou sel mixte de calcium nâa pu ĂȘtre identifiĂ© sur les foraminifĂšres dâOrbigny. Les vieillissements montrent que lâhumiditĂ© relative et la taille des spĂ©cimens jouent un rĂŽle primordial dans la formation des sels : des conditions humides favorisent la cristallisation du formiate de calcium sur le spĂ©cimen, tandis que l'acĂ©tate, trĂšs hygroscopique, est sujet aux cycles de dĂ©liquescence-cristallisation qui le conduisent Ă se disperser autour de lâĂ©chantillon lorsque celui-ci est tout petit. Enfin, pour mieux comprendre la prĂ©dominance du ÎČ-polymorphe du formate de calcium, diffĂ©rentes solutions de formiate de calcium ont Ă©tĂ© laissĂ©es Ă Ă©vaporer et placĂ©es dans des environnements Ă humiditĂ© variĂ©e afin dâĂ©tudier la transformation ÎČα. Lâanalyse semi-quantitative des produits montre que la prĂ©sence d'ions Ă©trangers tels que ceux prĂ©sents dans les coquilles de foraminifĂšres (Mg2+, Sr2+...) favorise lâĂ©mergence du ÎČ-polymorphe, et ralentit sa transition vers la phase stable.Ce travail montre que la nature des sels formĂ©s par la dĂ©gradation de Byne nâest pas seulement tributaire des COV prĂ©sents mais dĂ©pend aussi de la taille des spĂ©cimens, leur composition, la cristallisation de leur test et des cycles dâhumiditĂ© et de tempĂ©rature auxquels ils ont Ă©tĂ© soumis
Byne's Decay: Salt Crystallizations Threatening Calcareous Collections in Museum Environments
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Maladie de Byne : le cas de la collection de foraminifĂšres d'Alcide d'Orbigny
International audienceConsidĂ©rĂ© comme lâun des pionniers de la biostratigraphie et de la palĂ©ontologie française, Alcide Dessalines d'Orbigny (1802-1857) a portĂ© un intĂ©rĂȘt particulier Ă lâĂ©tude des fossiles de taille microscopique tout au long de sa vie. Câest ainsi quâil publia, avant dâentamer son voyage en AmĂ©rique, la toute premiĂšre classification des foraminifĂšres en 1826. En 1853, il devint le premier titulaire de la chaire de palĂ©ontologie du MusĂ©um national dâHistoire naturelle, discipline naissante dont la lĂ©gitimitĂ© sera longtemps discutĂ©e au sein du corps scientifique. Affaibli par ses voyages, dâOrbigny mourut seulement 4 ans aprĂšs sa nomination sans avoir pu donner au laboratoire de palĂ©ontologie lâessor dont il rĂȘvait. Sa collection dâinvertĂ©brĂ©s fossiles, dont lâinventaire mentionne plus de 100 000 piĂšces parmi lesquelles plus de 4000 foraminifĂšres, sera acquise par le MusĂ©um dĂšs 1858. Bien que les successeurs de dâOrbigny aient eu conscience de la valeur de cette collection, lâabsence de moyens matĂ©riels et humains conduira progressivement Ă sa nĂ©gligence, si bien que la maniĂšre dont les foraminifĂšres ont Ă©tĂ© conservĂ©s pendant 150 ans est aujourdâhui peu documentĂ©e
Alcide d'Orbigny and the Paris Foraminifera: story of a collection under Byne attack
International audienceIn 1858, the National Museum of Natural History, Paris, acquired the prestigious foraminiferal collection of the French naturalist Alcide Dessalines dâOrbigny (1802-1857). Pioneer in the fields of micropaleontology and biostratigraphy, dâOrbignyâs deep interest in tiny shells and micro-fossils led him to publish the first classification of the Phylum of Foraminifera in 1826. He later became the first professor of palaeontology at the Museum. However, quarrels in the teaching community resulted in multiple vacancies at the chair of palaeontology after dâOrbignyâs death. His collection, which includes about 800 slides of type specimens, 3D sculptures enlarged 40-200 times, hundreds of âunpublished platesâ and a thousand small bottles of sediments, was progressively abandoned. For almost a century, the foraminifera have been left to the care of scientists external to the museum. In 2007, a position of professor of micropaleontology was finally created and micropaleontological collections were gathered. Until then, the conditions of conservation of this outstanding scientific resource have been relatively unknown
Les pĂ©rĂ©grinations de la collection de ForaminifĂšres dâAlcide dâOrbigny au MusĂ©um dâHistoire naturelle de Paris : de la crĂ©ation dâune chaire de PalĂ©ontologie Ă lâavĂšnement de la micropalĂ©ontologie
International audienceAlcide dâOrbigny made his mark in the history of French Palaeontology by becoming, in 1853, the first holder of the chair of Palaeontology at the Museum of Natural History, Paris. His work on foraminifera made him one of the pioneers of Micropalaeontology. Today, his original collection of foraminifera, bought by the Museum after his death, represents one of the most prestigious collections of the institution. However, for more than a century, it had been relegated to the reserves and to the good will of a few enthusiasts, while the priority of research study was given to the large vertebrate fossils. It survived the conflicts that affected the Palaeontology department, and was moved in response to construction works, wars and natural accidents such as the great flood of 1910. These different events, combined with inappropriate storage conditions, probably caused the fragility of the specimens. In order to better understand this phenomenon, known as Byne's decay, research has been undertaken to reconstruct the various storage points of the collection from its acquisition to the present day. This article aims to demonstrate the close link between the Foraminifera Collection and the history of the chair of Palaeontology, through evidence drawn from the archives of the Palaeontology laboratory and the Museum of Natural History.Alcide dâOrbigny a marquĂ© lâHistoire de la PalĂ©ontologie française en devenant, en 1853, le premier titulaire de la chaire de PalĂ©ontologie du MusĂ©um dâHistoire naturelle de Paris. Les travaux quâil a menĂ©s sur les foraminifĂšres en ont fait lâun des pionniers de la micropalĂ©ontologie. Sa collection originale de foraminifĂšres, rachetĂ©e par le MusĂ©um aprĂšs sa mort, reprĂ©sente aujourdâhui lâune des collections les plus prestigieuses de lâinstitution. Pourtant, pendant plus dâun siĂšcle, celle-ci sera relĂ©guĂ©e aux rĂ©serves et Ă la bonne volontĂ© de quelques passionnĂ©s, tandis que la prioritĂ© de lâĂ©tude sera donnĂ©e aux grands vertĂ©brĂ©s fossiles. Elle survivra ainsi aux conflits qui toucheront le service de PalĂ©ontologie, et sera dĂ©placĂ©e au grĂ© des constructions, des guerres et des accidents naturels tels que la grande crue de 1910. Mais ces diffĂ©rents Ă©vĂ©nements, combinĂ©s Ă des conditions de stockage inappropriĂ©es, finiront par provoquer la fragilisation des spĂ©cimens. Dans lâoptique de mieux comprendre ce phĂ©nomĂšne, connu sous le nom de dĂ©gradation de Byne, des recherches ont Ă©tĂ© entreprises afin de reconstituer les diffĂ©rents points de stockage de la collection depuis son acquisition jusquâĂ nos jours. Ainsi, cet article tient Ă dĂ©montrer le lien Ă©troit entretenu entre la collection de foraminifĂšres et lâhistoire de la chaire de PalĂ©ontologie, Ă travers les tĂ©moignages tirĂ©s des archives du laboratoire de PalĂ©ontologie et du MusĂ©um national dâHistoire naturelle
Byne's Decay :The Case of Alcide dâOrbignyâs Foraminiferal Collection
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