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An early-branching microbialite cyanobacterium forms intracellular carbonates
A French team, led by Karim Benzerara (CNRS/IMPMC/ParisVI) and Purificacion Lopez-Garcia (CNRS/ESE/ParisXI) and including Sylvain Bernard (CNRS/LMCM/MNHN), discovered a new cyanobacterium in microbialites that forms intracellular Ca-Mg-Sr-Ba carbonate inclusions, revealing an unexplored pathway for calcification. Based on phylogenetic analyses, they tentatively name this cyanobacterium Candidatus Gloeomargarita lithofaciens. This discovery suggests that ancestral cyanobacteria may have biomineralized carbonates intracellularly and making them not prone to encrustation in extracellular precipitates. This might explain why cyanobacterial microfossils are missing in the oldest fossil stromatolites.
 
Image en microscopie électronique à balayage de deux cellules de Candidatus Gloeomargarita lithophora
SEM image of a specimen of Candidatus Gloeomargarita lithophora showing intracellular inclusions. © Karim Benzerara & Stefan Borensztajn

Reference: Couradeau E., Benzerara K., Gérard E., Moreira D., Bernard S., Brown Jr. GE., López-García P. 2012. An early-branching microbialite cyanobacterium forms intracellular carbonates. Science, Vol. 336, no. 6080, pp. 459-462. doi: 10.1126/science.1216171

To know more, click here (in french)
 


François Robert, 2011 recent recipient of the Leonard medal, speaks about Meteorites, cosmic messengers.
François Robert is head of the Laboratoire de Minéralogie et de Cosmochimie du Muséum, and Président du Programme National de Planétologie.
 
François Robert
To know more, click here (in french)


Prof. François Farges wrote a novel about the fascinating story on the Blue Diamond.
How it came from India to the court of King Louis XIV of France, how it disappeared during the French Revolution and why a secret copy of the stolen diamond was given to the Muséum by its robber. Over three centuries and three continents, dive into a forensic research after the greatest diamond ever cut by mankind.
 
about the Blue Diamond


54Cr-rich nanospinels identified in Orgueil.
An international team, including Laurent Remusat (CNRS/ MNHN Paris), combined the use of high resolution transmission electron microscopy, NanoSIMS and TIMS to identify the bearing phase of the 54Cr positive anomaly in Orgueil meteorite. The team, leaded by Nicolas Dauphas (Univ. Chicago) and including members of the California Institute of Technology, the University of Lille and the Museum d'Histoire Naturelle, has found one nanospinel with a 54Cr/52Cr isotopic ratio more than 4 times larger than the solar system value. These nanoparticles have likely been formed in a supernova that exploded shortly before the birth of the solar system and spread them into the dusty cloud that evolved into the solar system.
NanoSIMS image of the 54Cr/52Cr isotopic ratio showing an extremely enriched nanospinel among thousands of normal grains. Such grains are less than 100 nm wide.
Image caption: NanoSIMS image of the 54Cr/52Cr isotopic ratio showing an extremely enriched nanospinel among thousands of "normal" grains. Such grains are less than 100 nm wide.

Nicolas Dauphas, Laurent Remusat, James Chen; Mathieu Roskosz, Dimitri Papanastassiou, Julien Stodolna, Yunbin Guan, Chi Ma, and John Eiler.
"Neutron-rich chromium isotope anomalies in supernova nanoparticles"
The Astrophysical Journal, 720:1577-1591, doi:10.1088/0004-637X/720/2/1577

To know more, click here : University of Chicago - CNRS - MNHN - RFI (in french)

NanoSIMS data help link a new type of extremely primitive micrometeorites to comets.
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The Concordia station in Antarctica - Courtesy M. Munoz IPEV.
In a study led by Dr. Duprat and his micrometeorite hunting colleagues at the CSNSM Paris XI, a new type of extremely primitive micrometeorites obtained by melting and sieving ultra-clean snow in Antarctica, has yielded isotopic and mineralogic evidence for an outer Solar System origin. The NanoSIMS Service National was used to measure the hydrogen isotopic composition in two such micrometeorites that contain extremely deuterium-rich primitive organic materials from the coldest regions of the Solar System.
Science 328, 742-745 (2010)

Prof. Farges goes to India to shoot documentary about the Blue Diamond.
Prof Farges goes to India to shoot documentary about the Blue Diamond

After his discovery in the MNHN mineral collection of the lead-cast of the mythical Blue Diamond, which belonged to Louis XIV and was stolen during the revolution, the public interest has soared! A National Geographic Channel-ARTE-RAI collaboration is currently being shot in France, India, Belgium and the USA and will be broadcast around christmas 2010. In the photo, Prof. Farges is holding the replica of the "Tavernier Blue diamond" (115 carats) above the Krishna river valley at Kolluru, near Golconda, Andra Pradesh, India. The Blue Diamond was discovered here and brough back in 1668 by French traveller Jean-Baptiste Tavernier for Louis XIV. In the back, the mythic "mountain of the Eagles" described by Marco Polo and Simbad the Sailor in their legendary journeys to the "valley of the diamonds", guarded by "ferocious creatures".

The Paris CM chondrite is honored by being presented on the news on French TV. Paris is fresh and was less altered on its parent body than other CMs. It will be studied by a consortium of French laboratories to unravel early solar system history.
Météorite Paris
To know more, click here (in french) - Meteoritical Bulletin  - Abstract


Dr. Violaine Sautter from the LMCM speaks (in french) about the Mars Science Laboratory project and the laser system that will enable geochemical analyses of rocks at long distance:
Robot aux yeux chimiques
Collection « Des étoiles plein les yeux » réalisée par Paul de Brem et Olivier Le Bihan et produite par CNRS Images et le CNES


Chloé BRAHMI, PhD student at the LMCM, has been awarded a Fullbright Stipend and currently works on coral biomineralization at the University of Hawaii.
Chloé Brahmi
View from her office with Diamond Head in the background.


New book about meteorites by Matthieu Gounelle.
Que sais-je les météorites

Meteorite sheds light on birth of the solar system.
A team of the LMCM of the Muséum d'Histoire Naturelle (Paris), coordinated by PhD student Giacomo Briani (LMCM and Università di Firenze, Italy) and in collaboration with scientists of the Université des Sciences et Technologies (Lille) and of Université Joseph Fourier (Grenoble), have analysed an extremely primitive meteorite and discovered that it contains a unique and primordial rock fragment, which is thought to have remained largely unaltered since the solar system formed around 4.6 billion years ago. The data show unprecedented isotopic variations of nitrogen and pose serious problems for current astrophysical models of light element isotopic fractionation in the presolar nebula.
chondrite Isheyevo
Image caption: the central image is a high resolution SEM picture of the primordial inclusion discovered in the chondrite Isheyevo. The NanoSIMS images are maps of the 15N/14N distribution in the inclusion and clearly show the presence of several hotspots, i.e. localized enrichments in 15N, where the measured 15N/14N values are the most elevated for solar system material.

Briani G, Gounelle M., Marrocchi Y., Mostefaoui S., Leroux H., Quirico E. and Meibom A. (2009).
Pristine extraterrestrial material with unprecedented nitrogen isotopic variation
PNAS, doi:10.1073/pnas.0900197106

Chemistry World
L'EXPRESS (in French)


New tool in the study of marine carbonate biomineralization.
Based on the analytical capabilities of the NanoSIMS instrument at the Muséum d'Histoire Naturelle in Paris, in combination with the experimental facilities at the Centre Scientifique in Monaco, a new experimental method has been developed to label biomineralized carbonate structures with stable isotopes under essentially unperturbed growth conditions. These labeled structures can then be imaged with the NanoSIMS, which has a spatial resolution much better than 1 micrometer. Applied to corals, these new techniques immediately yield new insights into skeletal formation and hold the potential to rapidly advance the study of marine carbonate biomineralization.
porites
Image caption: The image shows a NanoSIMS image of a Porites coral skeleton labeled three times with 86Sr. All three labels are clearly imaged at a spatial resolution of about 200 nanometers. Below, insets showing morphological surface details of coral skeleton and a living coral nubbin in the aquarium during a labeling experiment.

Houlbrèque F., Meibom A., Cuif J.-P., Stolarski J., Marrocchi Y., Férriers-Pagès C., Domart-Coulon I., and Dunbar R. B. (2009)
Strontium-86 labeling experiments show spatially heterogeneous skeletal formation in the scleractinian coral Porites porites.
Geophysical Research Letters 36, L04604, doi:10.1029/2008GL036782.

Discovery of a unique micrometeorite.
Thanks to mineralogical, chemical and isotopic studies of a micrometeorite weighing a few micrograms, a franco-american team lead by Matthieu Gounelle identified a basaltic micrometeorite. It appears that this micrometeorite comes from a body so far unsampled by meteorite or micrometeorite collections. It significantly expands the inventory of planetary surfaces we can study in the lab. Results appeared on the 6th April issue of the Proceedings of the National Academy of Sciences. You can download the press release here and read this article in PNAS.
Micrométéorites
Glacial sand in the Cap Prudhomme moraine (Terre Adélie, Antarctica) is highly enriched in micrometeorites. A unique micrometeorite was found in 1994 by Michel Maurette. It is highly metamorphosed basalt unrelated to any other planetary surface in the solar system, providing clues on planetary crusts formation . Antarctica and glacial sand pictures: courtesy of Delphine Six (CNRS/UJF/OSUG) and Michel Maurette (CNRS-CSNSM) respectively. Art work: Michel Serrano.

Prof. Anders MEIBOM has received the European Mineralogical Union Medal for Research Excellence 2008 for his work in cosmochemistry, geochemistry and biomineralization.
Anders MEIBOM

To know more, click here

Découvertes majeures autour du diamant bleu de la couronne
Reconstitution virtuelle du diamant bleu de la couronne
La découverte récente d'une réplique historique en plomb du mythique diamant bleu, dans les collections du Muséum national d'Histoire naturelle, a permis la réédition exacte en réalité virtuelle puis en zircone (matériau imitant le diamant) de ce joyau royal, volé à la France en 1792. Les résultats de ces travaux, menés par François Farges sont publiés dans le volume 165 de la Revue de Gemmologie. Vous pouvez télécharger le communiqué de presse ici