Presence Of Apatite Research Articles

Reaction mechanisms of (RE0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 (RE = La or Yb) under CaO-MgO-Al2O3-SiO2 (CMAS) attack

In this study, two high-entropy ceramics, namely (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 (LaHZ) and (Nd0.2Sm0.2Eu0.2Gd0.2Yb0.2)2Zr2O7 (YbHZ), were prepared and investigated, in comparison to La2Zr2O7 (LZ). This investigation focused on their interactions with calcium-magnesium-alumina-silicate (CMAS), revealing noteworthy findings. High entropy samples particularly YbHZ exhibit significantly reduced infiltration depths compared to LZ. After CMAS corrosion, the reaction zones of LaHZ and LZ show a similar microstructure characterized by the presence of apatite and fluorite embedded in CMAS residue. In contrast, YbHZ forms a dense and nanoscale dual-phase zirconia (fluorite + pyrochlore) layer, with no visible CMAS residue. The different corrosion behavior is associated with the competition between fluorite and apatite phases, which is strongly related to the ionic radius of RE3+. Apart from the apatite, the formation of a dense and continuous fluorite Ca&RE-ZrO2 layer could also provide excellent CMAS resistance. These findings provide a viable strategy for designing CMAS-resistant materials.

Characterisation and Environmental Significance of Glauconite from Mining Waste of the Egorievsk Phosphorite Deposit

This article presents the results of a study of glauconite obtained from phosphate rock waste. The aim is to study the morphological, structural and chemical characteristics of glauconite and to determine the potential for secondary use of mining waste in the agricultural sector. The electromagnetic separation method was used to obtain glauconite concentrate. The optimum parameters for obtaining the maximum mineral content in the concentrate were determined. Studies have shown that glauconite is characterised by globular, granular grains of the highly mature variety. Glauconite almost invariably contains inclusions of pyrite and apatite, which significantly improve the characteristics of the fertiliser. Laboratory experiments have shown that glauconite waste and glauconite concentrate have a positive effect on plant growth and development. The high potassium content, the favourable globular shape of the grains, and the presence of apatite and pyrite inclusions indicate the potential use of glauconite from mining waste as a potash fertiliser. Application of glauconite fertiliser to the soil will provide an opportunity to improve its texture, providing better moisture and aeration. The use of glauconite fertiliser is particularly valuable on acidic soils where apatite can be dissolved, making phosphorus available to plants. This nutrient additionally favours plant growth, as well as reducing the risk of heavy metal accumulation in the soil. Thus, glauconite from the waste of the Egorievsk deposit represents a promising fertiliser for improving soil quality and increasing crop yields.

Petrology of an apatite-calcite segregationary kimberlite from the Andriesfontein pipe, Kaapvaal craton

Here, we present a case study of an apatite-calcite segregationary kimberlite from the Andriesfontein pipe (Kaapvaal craton) using EPMA and LA-ICP-MS data of olivine macrocrysts and groundmass phases to constrain magma evolution. The primary objectives are to first constrain magma evolution in the SCLM using olivine followed by late-stage evolution and the timing of fluid exsolution using groundmass phases and importantly, apatite. Olivine cores display a range in Mg# (87.2–93.6) with no distinguishable gap in compositions. Aluminium, however, clearly divides the cores into two populations: 1) high-Al cores (>100 ppm Al; >400 ppm Ca; Mg# 87.2–92.7; 52% of cores) interpreted to predominantly reflect the disaggregation of megacrysts, and 2) low-Al cores (<100 ppm Al; <200 ppm Ca; Mg# >92; 48% of cores) interpreted to reflect sampling of garnet peridotite at depths of 84.5–138 km estimated using the Al-in-olivine thermometer. Groundmass phlogopite and spinel are well-zoned recording evolution of the kimberlite melt with increasing oxidation state indicated by the presence of MUM spinel and tetraferriphlogopite rims. Perovskite trace elements concentrations are typical of kimberlite perovskite worldwide. Apatites are observed in late-stage segregations as both equant grains and radiating clusters of acicular laths, however, their compositions are identical (SrO ∼2.2 wt%, SiO2 < 1 wt%, and low REE e.g., La2O3 + Ce2O3 - <0.01 wt%). The relatively high SrO and low SiO2 suggests formation from a fluid phase rather than directly from the melt, consistent with the presence of apatite in segregations and predominantly acicular habit. Chondrite normalised REE profiles for apatite display sinusoidal patterns, which can be modelled by melt evolution through small degrees of predominantly perovskite fractionation. Ultimately, we present a five-stage model for melt evolution from melt-SCLM interactions to magma evolution through groundmass crystallisation and late-stage fluid exsolution, highlighting the complexity of kimberlite magma evolution from source to surface.

Influence of crystallographic anisotropy on the electrical conductivity of apatite at high temperatures and high pressures

Abstract The electrical conductivity of apatite single crystals along three main crystalline directions was measured in situ using a YJ-3000t multi-anvil apparatus and a combined system consisting of the impedance/gain-phase analyzer (Solartron 1260) and dielectric interface (Solartron 1296) at 973–1373 K and 1.0–3.0 GPa. The obtained results indicate that the relationship between the electrical conductivity and temperature conforms to the Arrhenius relation. At 2.0 GPa, the electrical conductivity of apatite with relatively high activation enthalpies of 1.92–2.24 eV shows a significant anisotropy with an extremely high anisotropic degree (τ = ~8–16) value. For a given [001] crystallographic orientation, the electrical conductivity of apatite slightly decreases with increasing pressure, and its corresponding activation energy and activation volume of charge carriers are 2.05 ± 0.06 eV and 9.31 ± 0.98 cm3/mol, respectively. All of these observed anomalously high activation enthalpy and positive activation volume values suggest that the main conduction mechanism is related to the monovalent fluorine anion at high temperature and high pressure. Furthermore, three representative petrological average schemes, including the parallel, Hashin-Shtrikman upper bound, and average models were selected to establish the functional relation for the electrical conductivity of the phlogopite-apatite-peridotite rock system along with the volume percentages of apatite ranging from 1 to 10% at 973–1373 K and 2.0 GPa. For a typical Hashin-Shtrikman upper bound model, the electrical conductivity-depth profile for peridotite containing the 10% volume percentage of apatite was successfully constructed in conjunction with our acquired anisotropic electrical conductivity results and available temperature gradient data (11.6 and 27.6 K/km) at depths of 20–90 km. Although the presence of apatite in peridotite cannot explain the high-conductivity anomalies in western Junggar of Xinjiang autonomous region, it may provide a reasonable constraint on those of representative apatite-rich areas.

Hydrolytic Degradation and Bioactivity of Electrospun PCL-Mg-NPs Fibrous Mats.

In this work, the in vitro degradation behavior of nanofibers was investigated in phosphate buffer solution (PBS) and simulated body fluid (SBF) to study their degradation behavior, as well as their bioactivity. The degradation was studied at different immersion times in order to evaluate how the presence of Mg-based nanoparticles can affect the degradation in terms of morphology, crystallinity, degradation rate and pH changes, and finally to evaluate the bioactivity of PCL-based electrospun nanofibers. We found that the degradation of the materials takes more than 3 months; however, the presence of nanoparticles seems to have an accelerating effect on the degradation of the electrospun nanofibers based on PCL. In fact, a reduction in diameter of almost 50% was observed with the highest content of both types of nanoparticles and an increase in crystallinity after 296 days of immersion in PBS. Moreover, the carbonyl index was calculated from an FTIR analysis, and a reduction of 20-30% was observed due to the degradation effect. Additionally, the bioactivity of PCL-based electrospun nanofibers was studied and the formation of crystals on the nanofibers surface was detected, except for neat electrospun PCL related to the formation of NaCl and apatites, depending on the amount and type of nanoparticles. The presence of apatites was confirmed by an XRD analysis and FT-IR analysis observing the characteristic peaks; furthermore, the EDX analysis demonstrated the formation of apatites than can be reconducted to the presence of HA when 20 wt% of nanoparticles is added to the PCL electrospun fibers.

A Multi-Analytical Investigation of Roman Frescoes from Rapoltu Mare (Romania)

(1) Background: Due to the precarious situation of many monuments or archeological sites, analytical investigations are necessary to obtain information about the used materials, as well as to identify the most appropriate solutions for their conservation/restoration. This paper addresses the characterization of mural painting fragments collected during the excavation in 2018 in Rapoltu Mare (La vie), Deva. (2) Methods: Specific analytical techniques were used, as follows: X-ray diffractometry (XRD), wavelength dispersive X-ray fluorescence (WDXRF), optical microscopy (OM), zoom microscopy and scanning electron microscopy (SEM), spectroscopic techniques (UV–Vis, FTIR, Raman), porosity and thermal analysis, all of which provide information about the structure, chemical composition, morphology and topography of pigments and their deterioration as well. (3) Results: Up to seven different pigments were identified: Egyptian blue, carbon, calcite, gypsum, hematite, goethite and green earth. Egyptian Blue is identified in all the other color areas, except the white area: in the green zone (as degradation product with beeswax) and in the red zone (in mixture with ochre) too. In addition, carbon and beeswax were highlighted as toner and binder for pigments, respectively. In the presence of the organic beeswax binding environment, the Egyptian blue pigment particles darkened or turned yellow significantly, changing the blue to a greenish color. It is also possible to identify wollastonite (CaSiO3) in the blue pigment, which indicates that the temperature used in the manufacturing of Egyptian blue was higher than 950 °C from thermal analysis. The presence of apatite, hematite and gypsum deposits in the Hunedoara region certifies that these pigments could have been of local origin, as demonstrated by the presence of analytically identified elements (Fe, P, S, Ca). (4) Conclusions: The analytical techniques used for such investigations have highlighted the main pigments used in Roman times for various Roman murals.

Process Mineralogical Assessment of the Grinding Products of the Per Geijer Iron Oxide-Apatite Deposits

ABSTRACT Information obtained from comminution test work at the laboratory scale can be utilized to characterize ore types and predict their behavior during comminution at the industrial scale. Comminution tests with a laboratory-scale rod and ball mill of 13 predefined ore types from the Per Geijer iron oxide-apatite deposits were conducted. The grinding setup refers to the so-called Malmberget method used at LKAB, characterized by a subsequent circuit of rod and ball mill grinding. The highest P80 values were obtained by grinding only in the rod mill for 10 min (step A). Ball mill grinding for 25 min (step B) and 35 min (step C) gave a very narrow range of P80 values. Hematite-dominated ore types had significantly higher P80 values after the primary grinding step A compared to the other ore types. Generally, Fe content increased in finer particle size classes while CaO and P contents decreased. The influence of silicates or phosphates is dependent on the dominant iron oxide. Magnetite-dominated ore types are more likely to be affected in their comminution behavior by the presence of silicate minerals. In contrast, hematite-dominant ore types are instead influenced by the presence of apatite. The difference in the degree of liberation of magnetite and hematite between ore types depends on size fractions rather than the amount of gangue in the ore most likely caused by very fine intergrowth of both iron oxides. A consolidation from 13 to 8 ore types is favored, supporting possible future mining of the Per Geijer deposits.

Mechanical Properties, Corrosion Resistance and Bioactivity of Oxide Layers Formed by Isothermal Oxidation of Ti-6Al-7Nb Alloy

Titanium and its alloys are among the most promising biomaterials for medical applications. In this work, the isothermal oxidation of Ti-6Al-7Nb biomedical alloy towards improving its mechanical properties, corrosion resistance, and bioactivity has been developed. The oxide layers were formed at 600, 700, and 800 °C for 72 h. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), 3D profilometry, and microindentation test, were used to characterize microstructure, surface geometrical structure, and the hardness of the diphase (α + β) Ti-6Al-7Nb alloy after oxidation, respectively. In vitro corrosion resistance tests were carried out in a saline solution at 37 °C using the open-circuit potential method and potentiodynamic measurements. Electronic properties in the air were studied using the Scanning Kelvin Probe (SKP) technique. The bioactivity test was conducted by soaking the alkali- and heat-treated samples in simulated body fluid for 7 days. The presence of apatite was confirmed using SEM/EDS and Fourier Transform Infrared Spectroscopy (FTIR) studies. The thickness of oxide layers formed increased with the temperature growth from 0.25 to 5.48 µm. It was found that with increasing isothermal oxidation temperature, the surface roughness, hardness, corrosion resistance, and contact potential difference increased. The Ti-6Al-7Nb alloy after oxidation revealed the HAp-forming ability in a biological environment.

Influence of Hydroxyapatite Nanospheres in Dentin Adhesive on the Dentin Bond Integrity and Degree of Conversion: A Scanning Electron Microscopy (SEM), Raman, Fourier Transform-Infrared (FTIR), and Microtensile Study.

An experimental adhesive incorporated with different nano-hydroxyapatite (n-HA) particle concentrations was synthesized and analyzed for dentin interaction, micro-tensile bond strength (μTBS), and degree of conversion (DC). n-HA powder (5 wt % and 10 wt %) were added in adhesive to yield three groups; gp-1: control experimental adhesive (CEA, 0 wt % HA), gp-2: 5 wt % n-HA (HAA-5%), and gp-3: 10 wt % n-HA (HAA-10%). The morphology of n-HA spheres was evaluated using Scanning Electron Microscopy (SEM). Their interaction in the adhesives was identified with SEM, Energy-Dispersive X-ray (EDX), and Micro-Raman spectroscopy. Teeth were sectioned, divided in study groups, and assessed for μTBS and failure mode. Employing Fourier Transform-Infrared (FTIR) spectroscopy, the DC of the adhesives was assessed. EDX mapping revealed the occurrence of oxygen, calcium, and phosphorus in the HAA-5% and HAA-10% groups. HAA-5% had the greatest μTBS values followed by HAA-10%. The presence of apatite was shown by FTIR spectra and Micro-Raman demonstrated phosphate and carbonate groups for n-HA spheres. The highest DC was observed for the CEA group followed by HAA-5%. n-HA spheres exhibited dentin interaction and formed a hybrid layer with resin tags. HAA-5% demonstrated superior μTBS compared with HAA-10% and control adhesive. The DC for HAA-5% was comparable to control adhesive.

Biogeochemical cycling of phosphorus in subsoils of temperate forest ecosystems

Tree roots penetrate the soil to several meters depth, but the role of subsoils for the supply of nutrient elements such as phosphorus (P) to the trees is poorly understood. Here, we tested the hypothesis that increased P deficiency in the topsoil results in an increased microbial recycling of P from the forest subsoil. We sampled soils from four German temperate forest sites representing a gradient in total P stocks. We analyzed the oxygen isotopic composition of HCl-extractable phosphate (δ18OP) and identified differences in P speciation with increasing soil depth using X-ray absorption near-edge structure (XANES) spectroscopy. We further determined microbial oxygen demand with and without nutrient supply at different soil depths to analyse nutrient limitation of microbial growth and used nanoscale secondary ion mass spectrometry (NanoSIMS) to visualize spatial P gradients in the rhizosphere. We found that δ18OP values in the topsoil of all sites were close to the isotopic signal imparted by biological cycling when oxygen isotopes in phosphate are exchanged by enzymatic activity. However, with increasing soil depth and increasing HCl-P concentrations, δ18Ο values continuously decreased towards values expected for primary minerals in parent material at depths below 60 cm at sites with high subsoil P stocks and below more than 2 m at sites with low subsoil P stocks, respectively. For these depths, XANES spectra also indicated the presence of apatite. NanoSIMS images showed an enrichment of P in the rhizosphere in the topsoil of a site with high P stocks, while this P enrichment was absent at a site with low P stocks and in both subsoils. Addition of C, N and P alone or in combination revealed that microbial activity in subsoils of sites with low P stocks was mostly P limited, whereas sites with high P stocks indicated N limitation or N and P co-limitation. We conclude that subsoil P resources are recycled by trees and soil microorganisms. With continued weathering of the bedrock and mobilisation of P from the weathered rocks, P cycling will proceed to greater depths, especially at sites characterised by P limitation.

Analysis of coloured Grooved Ware sherds from the Ness of Brodgar, Orkney

To the accumulation of evidence of painted decoration applied to Neolithic and Early Bronze Age pottery in Britain and elsewhere in Europe we report here the presence of decoration in red, black and white on some third millennium BC Grooved ware pottery at the Ness of Brodgar on Orkney. As expected, the red was identified as an iron-rich material and black was carbon black. The white was prepared from calcined (cow) bone; however, its identification encountered some issues arising principally from the effects of the prevailing burial conditions on the bone. Furthermore, whereas the chemical and FTIR data were consistent with the presence of apatite, XRD indicated that the white had a significant content of silicate minerals. This finding has suggested that the white required a preparatory step which might have included the calcined bone bring ground to powder in a stone mortar before application to the vessel surface. The results obtained at Ness of Brodgar are reviewed in the light of archaeometric data on similarly decorated prehistoric pottery reported from sites in Europe.

Mineral inclusion assemblage and detrital zircon provenance

Mineral inclusions are common in magmatic zircon and a potentially rich source of petrologic information. Controls on the relative proportions of inclusion phases, specifically early-crystallizing minerals such as apatite and late-crystallizing phases such as quartz, K-feldspar, and muscovite, have not been systematically studied. For instance, apatite dominates many magmatic zircon inclusion suites, and selective replacement of apatite over other phases has been proposed as a mechanism for generating apatite-poor inclusion assemblages in detrital zircons. However, the extent to which apatite inclusion abundance is influenced by source rock composition has not been established. The preservation of characteristic minerals in granite series, such as differences in magnetite and ilmenite abundances due to varying redox, have also not been systematically explored as inclusion phases in zircon. We surveyed zircon inclusion assemblages in Phanerozoic granitoids of a range of compositions and found a broadly inverse relationship between the presence of apatite in the inclusion suite and whole-rock SiO2 content. Selective loss of apatite is evident from deficits in apatite content among inclusions in contact with cracks in both detrital zircons and some granitoid zircons with independent evidence for fluid ingress (i.e., secondary phases filling open cracks). In cases where microstructural observations can identify primary inclusion assemblages (versus those impacted by fluid ingress), the relative occurrence of apatite can be used to broadly predict source rock SiO2 content. There is little relationship between whole-rock chemistry and the abundance of late-crystallizing phases or the relative proportions of quartz, plagioclase, and alkali feldspar. The presence of ilmenite not in contact with cracks in the host zircon likely points to origins in ilmenite-series (i.e., reduced) magmas, but the presence of magnetite is less diagnostic. Using the apatite abundance metric, detrital Hadean zircons from Jack Hills (Western Australia), appear to derive from felsic rather than intermediate or mafic granitoids and detrital Eoarchean zircons from Nuvvuagittuq Supracrustal Belt (Quebec) may derive from intermediate to felsic granitoids. No Fe-Ti oxides have been identified in Nuvvuagittuq zircons, but rare ilmenite in Jack Hills zircons points to origins of at least some part of the population in ilmenite-series magmas.

Carbonatite‐metasomatism signatures hidden in silicate‐metasomatized mantle xenoliths from NE China

Lithium isotopes measured in situ in minerals from typical silicate‐metasomatized mantle xenoliths from NE China show that olivine has higher Li abundances of 1.2–4.0 ppm and higher δ7Li values of −0.12–15.46‰ than those in orthopyroxene (Li = 0.56–3.0 ppm; δ7Li = −11.84–7.31‰) and clinopyroxene (Li = 0.21–2.1 ppm; δ7Li = −9.81–14.75‰). The Li distributions between these coexisting minerals show a prominent signature of carbonatite metasomatism. The correlation of δ7Li with Li abundance in orthopyroxene is in accordance with petrological expectation of preferential reaction of orthopyroxene with carbonatite melt. The carbonatite metasomatic agent inferred from the Li isotope systematics is compatible with petrological and geochemical features such as the presence of apatite, appearance of wehrlite, and presence of high‐Mg# minerals and low Ti/Eu in clinopyroxene. The complicated Li isotope composition of olivine implies that carbonatite metasomatism occurred after silicate metasomatism. These features indicate that the predominant silicate metasomatism is extensively recorded by petrology, mineralogy, and geochemistry, whereas Li isotope systematics is more sensitive to subordinate carbonatite metasomatism. The metasomatic melts are inferred to be relatively enriched in 6Li and thus suggests that they were probably derived from a highly dehydrated slab.

Geology and mineralogy of the Ashram Zone carbonatite, Eldor Complex, Québec

The Ashram Zone, which is host to the Ashram Rare Earth Element (REE) Deposit, occurs within the Eldor Carbonatite Complex, Québec, Canada. The complex is located within the Paleoproterozoic New Québec Orogen (Labrador Trough), and has been subjected to greenschist metamorphism and folding during the Hudsonian Orogeny at 1.75Ga. To date, consanguineous undersaturated alkaline rocks have not been recognized within or adjacent to the complex. It is evident that the bulk compositions of the rocks, essentially magnesiocarbonatites and ferrocarbonatites, do not represent those of liquid compositions, as many are complex breccias which have been subjected to later hydrothermal activity. The Ashram Zone is dominated by diverse textural varieties of carbonatite which include: fluorite-rich schlieren carbonatites; coarse-to-medium grained granular carbonatites; fine grained, commonly mosaic-textured, quartz-bearing carbonatites; and colloform carbonatites. Compositional and textural data are provided for the minerals present in the carbonatites. The major rock-forming minerals are diverse Ca-Mg-Fe carbonates, fluorite, and quartz. The carbonates range in their compositional evolution from rare dolomite through ferrodolomite and magnesian siderite to siderite. The principal REE-bearing minerals of the Ashram Deposit are monazite-(Ce) and monazite-(Nd), with lesser amounts of bastnaesite-(Ce) and bastnaesite-(Nd). The minor and accessory mineral suite is characterized by the presence of apatite, phlogopite, xenotime, diverse Sc- and sn-bearing Nb-Ti-minerals (niobian rutile, nioboaeschynite, samarskite), barite, sphalerite, several uncommon, but here relatively abundant, Ba- and Ba-Be minerals (bafertisite, magbasite, barylite, betrandite, sanbornite, cebaite), yangzhumingite, cassiterite, galena, pyrite, and rare magnetite and potassium feldspar. Pyrochlore is absent and the Nb-Ti oxide assemblage is similar to that found in NYF-pegmatites associated with F-rich, A-type granitoids. The mineralogy of the Ashram Deposit, compared to that of other carbonatites associated with undersaturated silicate rocks is unique, especially with respect to the abundance of fluorite and monazite (commonly with Nd-enrichment), Ba-Be-enrichment, the NYF-type Nb-Ti oxide assemblage (especially xenotime, Y-Nb-aeschynite, samarskite), phlogopite-potassium feldspar quartz-rich residua with granitoid characteristics, paucity of magnetite, pyrochlore, and Sr-bearing carbonates. The Ashram Deposit is considered to be a late-magmatic-to-hydrothermal F-REE magnesio-to-ferrocarbonatite derived from as yet unknown consanguineous antecedents.

Geochemistry of S, Cu, Ni, Cr and Au-PGE in the garnet amphibolites from the Akom II area in the Archaean Congo Craton, Southern Cameroon

The fresh and weathered garnet amphibolites, from the Akom II area in the Archaean Congo Craton, were investigated to determine the S, Cu, Ni, Cr, and Au-PGE values. The garnet amphibolites are composed of amphibole, plagioclase, garnet, quartz, and accessory apatite, spinel, sericite, pyrite, chalcopyrite and non-identified opaque minerals. The presence of apatite, sericite, and two generations of opaque minerals suggests that they might be affected by hydrothermal alteration. They are characterized by moderate Al2O3, Fe2O3, CaO, V, Zn, and Co contents with negative Eu- and Ce-anomalies. The sulfur concentrations are variable (380–1710ppm). According to the sulfur contents, amphibolites can be grouped into two: amphibolites with low contents, ranging between 380 and 520ppm (av.=457ppm); and amphibolites with elevated contents, varying from 1140 to 1710ppm (av.=1370ppm). Amphibolites contain contrast amounts of Cu (∼1800 to 5350ppm) while nickel contents attain 121ppm. Chromium contents vary from 43 to 194ppm. Sulfur correlates positively with Cu and Cr, but negatively with Ni and Ni/Cr ratio. The total Au-PGE contents attain 59ppb.The presence of amphibole and feldspars confirms the low degree of amphibolite weathering. The secondary minerals are constituted of kaolinite, gibbsite, goethite and hematite. Despite the accumulation of some elements, the major and trace element distribution is quite similar to that of fresh amphibolites. Nevertheless, the weathering processes lead to the depletion of several elements such as S (239–902ppm), Cu (520–2082ppm), and Ni (20–114ppm). Chromium and Au-PGE show an opposite trend marked by a slight enrichment in the weathered amphibolites. Amidst the Au-PGE, Pd (60ppb) and Pt (23ppb) have elevated contents in the fresh rocks as well as in the weathered materials. The PPGE contents are much higher than IPGE contents in both types of materials. The Pd/Pt, Pd/Rh, Pd/Ru, Pd/Ir, Pd/Os, and Pd/Au values indicate that Pt, Rh, Ru, Ir, Os and Au are more mobile than Pd. Chondrite-normalized base metal patterns confirm the abundance of Pd and the slight enrichment of Au-PGE in weathered rocks. Palladium, Rh and Ir are positively correlated with S. Conversely Pt and Ru are negatively correlated with S and Au is not correlated with S. Despite the high and variable S and Cu contents, the garnet amphibolites possess low Au-PGE and other base metals contents.

Sedimentological study of major paleonto-archaeological localities of the Late Pliocene Quranwala zone, Siwalik Frontal Range, northwestern India

Since 2008, the Indo-French research program ‘Siwaliks’ has been prospecting in the Late Pliocene formations of the Chandigarh anticline in the Northwest of India (Siwalik Frontal Range, Himalayan foothills). More than 200 quartzite tools and 1500 terrestrial vertebrate fossils have been collected from a Pliocene continental formation near the village of Masol. Several fossils show exceptional cut marks. A complete geological investigation of this area was performed in order to reconstruct the paleoenvironment. The geological sequences of the three major paleonto-archeological localities, Masol 1, Masol 6 and Masol 13, were studied. Silt and sandstone samples of the Quranwala fossiliferous area were collected to correlate the stratigraphy among the three localities and to understand the origins of the sediments. Three different techniques were used to analyze the sediments: a granulometric approach, X-ray diffraction and an analysis of heavy minerals. The sediment analysis demonstrates the relationship between the sample collected in Masol and the dismantling of the Higher as well as of the Lesser Himalaya. During the Late Pliocene, Masol was a floodplain with rich continental and freshwater fauna. The rivers were relatively calm, as indicated by the presence of apatite. Despite this, the quasi-simultaneous accumulations of quartzite cobbles and clay, as well as the presence of carcasses of small and large herbivores, suggest sudden climate variations probably due to the monsoon.

Uranium mobilization by fluids associated with Ca–Na metasomatism: A P–T–t record of fluid–rock interactions during Pan-African metamorphism (Western Zambian Copperbelt)

A dozen uranium occurrences are known in the Western Zambian Copperbelt (Domes region, Zambia). The host-rocks, Neoproterozoic kyanite±talc micaschists, have been interpreted as meta-evaporites that formed part of an epicontinental sequence affected by upper amphibolite metamorphism during the Pan-African orogeny. Ca–Na metasomatism, expressed by the presence of apatite, epidote and scapolite, is regionally extensive in the Katanga and the pre-Katanga rocks in the Domes region. The present study focuses on the Solwezi dome in the Western Zambian Copperbelt. Two distinct uranium mineralization events that took place here mark the transition from crustal-thickening by tectonic accretion to exhumation of the metamorphic host rocks.U–Pb dating of uraninite and Th–Pb dating of monazite show that the first U-mineralization event took place between ~550Ma and ~530Ma. The event is therefore contemporaneous with crustal thickening and, on the basis of fluid inclusion analyses, can be related to circulation of hypersaline Ca-rich metamorphic fluids trapped at minimum P–T conditions of 460MPa and 500°C. On a regional scale, the event is related to an epidote–apatite metasomatic assemblage. The second mineralization event, dated at between ~510 and ~500Ma by Th–Pb dating of monazite, is related to high-salinity Ca–Na-rich metamorphic fluids and occurred during exhumation of the high-grade metamorphic rocks. These fluids were trapped at the ductile/brittle transition at 150 to 260MPa and 200 to 300°C. A regional-scale scapolitization is attributed to these late fluid circulations. These fluid–rock interactions, described at the regional scale, are also characterized at the mineral scale. Alteration reactions, assisted by CaCl2-rich fluids, indicate that monazite and allanite hosted by the pre-Katanga rocks potentially acted as U sources for these Pan-African synmetamorphic uranium mineralizations.

Bioactivity Improvement of Forsterite-Based Scaffolds with nano-58S Bioactive Glass

Forsterite-based composite scaffolds with interconnected pore architecture were successfully manufactured via selective laser sintering. The nano-58S bioactive glass (BG) was added to forsterite for purpose of improving the bioactivity of the composite scaffolds. The effect of nano-58S BG contents on the biological behavior and mechanical properties was investigated. The results showed that the composite scaffolds could induce the formation of apatite compared with the pure forsterite scaffolds. Moreover, with increasing nano-58S BG, the scattered spherical apatite particles accumulated continuously and covered the whole surface. At last the apatite layer became sponge-like shape. The presence of apatite was confirmed with scanning electron microscopy equipped with energy dispersive spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy. In addition, MG-63 cells adhesion was enhanced with increase in the amount of the nano-58S BG. Besides, the maximum compressive strength was 43.9 ± 1.1 MPa when the nano-58S BG was 20.0 wt%. This study indicated that the composite scaffolds have a potential for bone tissue engineering.

Frothing Phenomena in Phosphate Gangue Flotation from Magnetite Fines with Fatty Acid based Collector and MIBC Frother

Dephosphorization of magnetite fines at LKAB is carried out by floating the phosphorous gangue using a fatty acid based collector namely Atrac and MIBC frother. Excessive and stable froth formation in flotation led to an unnecessary step of diluting the phosphate froth gangue component to transport to tailings damn. In this study the influence of reagents and their combinations on the froth production and stability was examined. Methods involved surface tension measurements, froth production and froth quality tests, zeta-potential and spectroscopy methods to resolve the possible collector and frother interactions. The froth production and quality was evaluated in the presence of apatite and magnetite solid particles as well. The volume and quality of froth produced by Atrac was found to be a function of concentration and pH, while MIBC formed non-stable froth with approximately the same volume independent of concentration. When Atrac is combined with MIBC the froth production and quality is enhanced. As no interaction was detected between the reagents, the increase of froth production is thought to be a change in electrostatic forces around the collector molecule by the frother. Atrac has a higher contribution to frothing than MIBC. Surface active partially hydrophobic apatite particles were observed to be the main factor causing extremely stable froth.

Characteristics of Soil Phosphorus in Tree Island Hardwood Hammocks of the Southern Florida Everglades

The Florida Everglades is a P limited, freshwater wetland ecosystem. In many cases, soil P concentrations in tree islands in the Everglades greatly exceed concentrations in the surrounding marsh; however, little information is available regarding the characteristics of P in tree island soil. Surface soil samples from 26 tree islands were analyzed for total elements, distribution of soil P forms, and soil mineralogy. Total phosphorus (TP) concentrations of soil ranged from 0.764 to 88.1 g kg–1. Most (&gt;80%) of the TP in high P hammock soils was bound in an inorganic form (HCl‐extractable), while organic P accounted for a relatively small (∼10%) proportion. Total P was positively correlated with non‐carbonate inorganic soil matter (i.e., non‐carbon matter, r = 0.98, p &lt; 0.001), non‐carbonate calcium (NCCa, r = 0.98, p &lt; 0.001), and HCl‐extractable phosphorus (HCl–P, r = 0.997, p &lt; 0.001). Apatite was identified by X‐ray diffraction (XRD) in soils with elevated P concentration. These soils also contained bone fragments. The high proportion of HCl–P observed in tree island soil coupled with a positive relationship between NCCa and P concentration is evidence for an exogenous P source. The presence of apatite and bone fragments in tree island soils indicates that deposition of biogenic apatite contributes to the soil P pool.