B22-Multimode InfraRed imaging And Microspectroscopy
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Marta
Morana
,
Lorenzo
Barni
,
Haixing
Fang
,
Giulia
Marras
,
Gianfelice
Cinque
,
Antonio
Angellotti
,
Fabrizio
Nestola
,
Alla
Logvinova
,
Denis
Mikhailenko
,
Luca
Bindi
,
Vincenzo
Stagno
Diamond Proposal Number(s):
[35052]
Open Access
Abstract: The investigation of mineral inclusions in diamonds represents a unique tool to better understand the mineralogy and composition of hidden portions of Earth's mantle and, hence, determine conditions of pressure and temperature at the time of diamond formation. Using a combination of experimental techniques and different geothermobarometric approaches, we characterized a natural diamond from Udachnaya kimberlite pipe entrapping nine inclusions; the inclusions are five garnets, three clinopyroxene and one sulfide and represent an eclogitic paragenesis. Here, we adopted, for the first time, the elastic geobarometry method to the garnet-diamond inclusion-host system to calculate the entrapment conditions for the diamond-garnet pair, resulting in 5.7(±0.3) GPa at 1154 °C. These P-T data are compared with estimates obtained through chemical geothermobarometry, employing T projection onto the local geotherm, a common approach used for eclogite xenoliths in absence of robust calibrated barometers. Our data demonstrate that elastic geobarometry for the garnet-diamond pair results to be a very reliable tool to determine the diamond formation also for eclogitic systems and this will allow to expand our knowledge on eclogitic diamonds in terms of depth of formation.
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Nov 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[32381]
Abstract: This study aimed at determining Ni and Co leaching kinetics from a New Caledonian laterite in an acidic medium (H2SO4 pH 1.5) and in a reductive environment (addition of SO32− or Fe(II)) at 46 °C. The mineralogical study revealed that Co was mainly carried by Mn oxyhydroxides in the limonite sample. Conversely, Ni was hosted by both Fe and Mn oxyhydroxides. In the presence of a reductive reagent, Mn oxyhydroxides dissolved rapidly compared to goethite, the main Fe oxyhydroxide in the sample. Co, Mn and Ni reductive leaching yields reached 79 %, 83 % and 9 % respectively after 2 days. Based on these results, a Mn oxides concentrate was produced in order to efficiently leach Co while limiting Fe oxyhydroxide dissolution. This concentrate resulted from a combination of particle size and gravity separation steps. The volume/mass of sample was drastically decreased since the mass of the final sample was only 3.3 % of the initial one. Co content increased from 0.16 wt% in the limonite to 2.3 wt% in the concentrate, representing an enrichment factor of 13.8 and recovery yield of 60 %. Co, Mn and Ni leaching yields reached 87 %, 95 % and 80 % respectively in the Mn oxides concentrate leaching experiment. The difference in Ni behaviour was consistent with the mineralogical composition: Ni was mainly carried by the goethite in the laterite, while it was hosted mainly by the Mn oxyhydroxides in the Mn oxides concentrate. This study gives a proof of concept for the development a robust pre-concentration process to recover Co.
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Nov 2025
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E01-JEM ARM 200CF
E02-JEM ARM 300CF
I18-Microfocus Spectroscopy
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N.
Topping
,
J. C.
Bridges
,
L. J.
Hicks
,
L.
Petera
,
C. S.
Allen
,
J.
Ryu
,
D. G.
Hopkinson
,
M.
Danaie
,
L.
Blase
,
F. M.
Willcocks
,
G.
Douglas
,
H. G.
Changela
,
T.
Noguchi
,
T.
Matsumoto
,
A.
Miyake
Diamond Proposal Number(s):
[30752, 31953, 32874, 35976, 29615, 31641, 35046]
Open Access
Abstract: A correlative multi-technique approach, including electron microscopy and X-ray synchrotron work, has been used to obtain both structural and compositional information of a sulfur-bearing serpentine identified in several carbonaceous chondrites (Winchcombe CM2, Aguas Zarcas CM2, Ivuna CI, and Orgueil CI), and in Ryugu samples returned by the Hayabusa2 mission. S-K edge X-ray absorption spectroscopy was used to determine the oxidation state of sulfur in the serpentine in all samples except Ryugu. The abundance of this phase varies across these samples, with the largest amount in Winchcombe; ~12 vol% of phyllosilicates are identified as sulfur-bearing serpentine characterized by ~10 wt% SO3 equivalent. HRTEM studies reveal a d001-spacing range of 0.64–0.70 nm across all sulfur-bearing serpentine sites, averaging 0.68 nm, characteristic of serpentine. Sulfur-serpentine has variable S6+/ΣStotal values and different sulfur species dependent on specimen type, with CM sulfur-bearing serpentine having values of 0.1–0.2 and S2− as the dominant valency, and CIs having values of 0.9–1.0 with S6+ as the dominant valency. We suggest sulfur is structurally incorporated into serpentine as SH− partially replacing OH−, and trapped as SO42− ions, with an approximate mineral formula of (Mg Fe2+ Fe3+ Al)2-3(Si Al)2O5(OH)5-6(HS−)1-2(SO4)2−0.1-0.7. We conclude that much of the material identified in previous studies of carbonaceous chondrites as TCI-like or PCPs could be sulfur-bearing serpentine. The relatively high abundance of sulfur-bearing serpentine suggests that incorporation of sulfur into this phase was a significant part of the S-cycle in the early Solar System.
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Nov 2025
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B22-Multimode InfraRed imaging And Microspectroscopy
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A.
Angellotti
,
M.
Morana
,
L.
Barni
,
G.
Cinque
,
Y.
Lu
,
R.
Tao
,
G.
Marras
,
A.
Logvinova
,
L.
Bindi
,
D.
Mikhailenko
,
V.
Stagno
Diamond Proposal Number(s):
[35052]
Open Access
Abstract: Natural diamonds are exceptional carriers of mineralogical and chemical information from inaccessible depths of our planet. During their crystallization, they can host light elements such as H and N preserving a natural archive of mantle chemistry that, in turn, allows a better understanding of the chemical composition of the growth media, mechanisms of their formation and residence temperatures in the interior of Earth. However, how N and H distribute near entrapped minerals is still unknown. In this study we investigated the effect of chromite mineral inclusions on the spatial distribution of nitrogen and hydrogen in two natural diamonds of peridotitic origin using in situ synchrotron-based Fourier transform infrared microspectroscopy. From the acquisition and optimization of high-resolution maps, we determined the distribution of nitrogen, hydrogen, and nitrogen aggregation state.
Our results reveal a dependence between the absorption of H-related peaks with the incorporation of pairs of nitrogen atoms (NA-centers). We explain it as indication that chemical interactions between chromite and H might be masked by variations in the N aggregation state. We also conclude that synchrotron micro-FTIR is an advanced technique to assist the synthesis of N- (and H-) doped diamonds for industrial applications.
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Nov 2025
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I18-Microfocus Spectroscopy
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Ian T.
Burke
,
Patrizia
Onnis
,
Alex L.
Riley
,
Catherine J.
Gandy
,
Violeta
Ramos
,
Gavyn K.
Rollinson
,
Patrick
Byrne
,
Richard A.
Crane
,
Karen A.
Hudson-Edwards
,
Elin
Jennings
,
William M.
Mayes
,
J. Frederick W.
Mosselmans
,
Adam P.
Jarvis
Diamond Proposal Number(s):
[29808, 31675]
Open Access
Abstract: The erosion of legacy coastal municipal solid waste landfill sites will result in the dispersion of particulate material into nearby ecosystems with potential for effects on marine populations. Information on the speciation and solid phase associations of metal(loid) contaminants will help to predict contaminant behaviour and better understand ecosystem risks. Here, we investigate the solid phase composition of, and metal(loid) leaching from, fine fraction materials recovered from three actively eroding coastal landfill sites. High concentrations of a range of potentially toxic elements (As, Cd, Cr, Cu, Pb, Ni and Zn) were present in multiple samples, but metal(loid) leaching rates were very low (≪1 wt%) in both deionised water and seawater solutions. Therefore, particulate dispersion is the most likely mode of contaminant transport occurring at these sites. The fine fraction materials were dominated by fine sand sized (63–180 μm) quartz grains and silt sized (<63 μm) matrix components, which were likely to be poorly retained on beaches and easily transported offshore. Four priority contaminants (As, Cu, Pb and Zn) were found to occur primarily in adsorbed or precipitate forms, as either coatings on other particles or as discrete <10 μm particles. Dilution of these fine-grained contaminated particles within natural pelitic sediments will likely reduce the overall ecosystems impacts; but the risks to filter and bottom feeding organisms, and the potential for biomagnification across trophic levels are poorly understood.
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Oct 2025
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[35733]
Open Access
Abstract: This research examines the dynamics of reactive CO2 transport in carbonate rock, focusing on the impact of carbonic acid-induced formation damage. We provide real-time visualization of these processes by employing four-dimensional (4D) high-resolution synchrotron imaging at the I13 beamline hosted at the Diamond Light Source. We visualize and quantify the temporal effects of reactive CO2 transport at the pore scale in carbonate rock. The experiment involved injecting CO2-saturated brine through the sample with in situ scanning to track the different stages of chemical dissolution. Analysis of the images shows a channelled dissolution pattern which corresponds with a gradual increase in porosity due to pore structure changes. Pore network models were generated from the segmented images to carry out a sequence of drainage and imbibition simulations. The result demonstrated that reduced capillary entry pressure with increased pore connectivity after dissolution. Furthermore, the trapping efficiency was quantified to predict a slight decrease in dissolution as the pores become broader and better connected.
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Oct 2025
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[39923]
Abstract: Climate change is accelerating sea-level rise (SLR), increasing the intensity and frequency of saltwater intrusion, and coastal storm flooding. Areas that are heavily contaminated with pollutants such as arsenic (As) in coastal areas may be influenced by tidal cycles. The effects of seawater intrusion and prolonged flooding will drive chemical and mineralogical changes which may threaten water quality and coastal ecosystem health. We investigated the re-mobilization of As from heavily contaminated urban sediments (13.3 g kg-1 As), over a seawater salinity gradient for 35 d combining anoxic incubation and X-ray absorption spectroscopy. We observed that As mobility is closely related to the reductive dissolution of Fe oxyhydroxides because the variation of ~1.3% of the total Fe dissolution was associated with ~9% of total As release in solution. Sulfidation boosted by salinity increased FeIII-mineral reductive dissolution, which increased As release at short term incubation (before 14 d), however at long term incubation (at 35 d), sulfidation also re-immobilized the soluble As to stable new solid phases such as Asx-Sy minerals and coprecipitation/adsorption with FeS minerals. Our results demonstrate the threat that SLR has on As release and immobilization from contaminated coastal sediments or soils due to biogeochemical redox cycling of Fe and S.
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Oct 2025
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Open Access
Abstract: The release of geogenic arsenic into groundwater, driven by reductive dissolution of Fe(III)/As(V) oxide phases, poses a severe health risk to millions in South and Southeast Asia. However, the microbes and electron donors responsible for the reductive dissolution remain unclear, due to complex a(biotic) interactions in sediments (traditionally used in microcosm incubation studies). In this study, indigenous microbial communities were sampled from arsenic-prone aquifers in Kandal Province, Cambodia, by filtering groundwater through sands coated with Fe(III)/As(V) minerals. This provided a streamlined inocula to study fundamental Fe(III)/As(V) reduction processes in controlled laboratory experiments. Anoxic incubations with contrasting electron donors suggested that biolabile organics are the main drivers of Fe(III) and As(V) reduction in the sampled aquifers, but methane can also contribute to Fe(III) reduction (at a slower rate) in the absence of labile organics. Known Fe(III)-reducing bacteria (e.g. Geobacter and Geothrix) were implicated in Fe(III)/As(V) reduction. Methane-driven Fe(III) reduction appeared to be mediated by proteobacterial methanotrophs (e.g., Methylomonas and Methylosinus), either directly or via symbiotic interactions with Geobacter through labile organic intermediates (suggested by acetate generation) highlighting the flexibility of proteobacterial methanotrophs under anoxic conditions. No methane-driven As(V) reduction was implicated in this study, while nominal As(V) reduction driven by aquatic organics (sorbed from the groundwater during filtration) was evident in control incubations suggesting some decoupling between Fe(III) and As(V) reduction. Furthermore, the sand filtration approach offers a promising method for producing simplified inocula for further studies of microbe-organic-mineral interactions in arsenic-prone aquifers and other complex biogeochemical systems.
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Oct 2025
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B24-Cryo Soft X-ray Tomography
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Diamond Proposal Number(s):
[38716]
Open Access
Abstract: Filamentous microbial biosignatures associated with iron sulfides are among the prime targets in early life studies, but their formation and preservation are insufficiently understood. Here, we experimentally evaluated the taphonomy of filamentous sulfur-oxidizing bacteria exposed to iron–sulfur–rich conditions and high temperatures (≤ 80 °C), mimicking burial diagenesis and/or hydrothermal alteration. The addition of ferrihydrite and sulfide at 22 °C resulted in a near-instantaneous formation of iron sulfides. Heating to 80 °C for 2–6 weeks resulted in the formation of polysulfides and magnetic Fe- and/or S-containing minerals, with low pyritization (~ 11%). Notably, Fe–S mineral formation was only loosely associated with the filaments. However, intracellular elemental sulfur released from the sulfur-oxidizing bacteria re-precipitated extracellularly, coating individual filaments, possibly promoting the formation of pyritic crusts during later diagenetic stages. Taken together, our study revealed that biosignatures in filamentous sulfur mats might be preserved in a variety of environments, including hydrothermal systems on and beyond the Earth.
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Oct 2025
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[22220]
Open Access
Abstract: Sulfurisation of organic matter (OM) is a prominent preservation mechanism, however iron sulfide precipitation, particularly pyrite (FeS2), can counteract this mechanism. There is a dearth of high-resolution, spatially-resolved spectroscopic (redox) information on sulfur and iron inventories within organic-rich rocks that would improve our understanding of prevailing environmental conditions during deposition. Here, state-of-the-art synchrotron-based X-ray absorption and fluorescence analyses of key organic- and sulfur-rich mudstones demonstrate the potential of these techniques to non-destructively map and produce detailed spectroscopic information. Detailed high-resolution analyses (μm- to mm-scale) reveal the presence of widespread sulfurised OM in the Blackstone Band of the Kimmeridge Clay Formation, in line with a persistence of euxinia over a long temporal span and low reactive iron input, facilitating the preservation of OM through sulfurisation. In contrast, the presence of sulfurised OM was transitional in the Monterey Formation, consistent with fluctuating water column redox conditions, and is less significant in the Whitby Mudstone Formation, likely due to the high reactive iron concentrations outcompeting sulfurised OM formation. Analyses of sulfur species using model compounds further indicate that the Whitby Formation is strongly enriched in inorganic reduced sulfur minerals, while both the Kimmeridge Clay and Monterey Formations are dominated by organic sulfur species. These synchrotron-based observations improve our understanding of environmental conditions during the time of deposition of these mudstones and thus show great promise in the study of organic-rich sediments, especially in allowing their depositional settings to be more accurately reconstructed.
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Sep 2025
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