Wavelength-dispersive Electron Microprobe Research Articles

Glass from the 11th–13th century medieval castle of San Giuliano (Lazio Province, Central Italy)

Compositional analysis of glass from the medieval castle of San Giuliano (Lazio, Italy), occupied from approximately CE 1050–1250, sheds light on the financial wherewithal and integration of the castle’s elite inhabitants into wider economic networks. Portable X-ray fluorescence (pXRF) of 261 shards was used to select 32 for further analysis using wavelength dispersive electron microprobe analysis (EMPA-WDS). This compositional analysis documents the pervasive recycling of earlier glass cullet, some of which pre-dates the 4th century CE. Around 20% of the sample comprised primarily plant ash glass, evidencing the penetration of plant-ash glasses into inland sites on the western central Italian peninsula. Almost 60% of the shards were an intermediate glass combining more recent plant ash glasses with recycled natron-based glass cullet derived from the Roman and Early Medieval periods. Compared to glass assemblages from contemporaneous sites, the levels of both recycled and intermediate glasses are quite high, with a concurrent incidence of trace elements that further precluded the manufacture of perfectly translucent glass vessels. This suggests that while the residents of the castle desired glass as a symbol of prestige, they may not have had the economic resources to obtain glass of the highest quality.

The atomic arrangement and electronic interactions in vonsenite at 295, 100, and 90 K

Abstract Vonsenite, Fe22+Fe3+O2BO3, has been the subject of many studies in the materials science and condensed matter physics communities due to interest in the electronic and magnetic properties and ordering behavior of the phase. One such study, undertaken on synthetic material of end-member composition, reports X-ray diffraction structure refinements that indicate a phase transition from Pbam to Pbnm at or just below ~283 K, determined subsequently to arise from a Peierls-like instability. To compare the stability of the natural phase with that of synthetic material, we performed high-precision X-ray crystal-structure analyses at 295, 100, and 90 K (R1 = 0.0119, 0.0186, and 0.0183, respectively), Mössbauer spectroscopy at 295, 220, 150, 80, and 4.2 K, and wavelength-dispersive electron microprobe analysis on a vonsenite of near-end-member composition from Jayville, New York, U.S.A. The Pbnm structure is observed at 100 and 90 K, suggesting similar phase stability for the natural and synthetic phases. Comparison of Mössbauer data and X-ray site occupancies between the natural and synthetic phases suggests a reinterpretation of Mössbauer site assignments. We conclude that the Peierls-like instability underlying the reported transition from Pbam to Pbnm in synthetic material also occurs in our specimen of natural near-end-member vonsenite at temperatures between 295 and 100 K.

Petrography of the carbonaceous, diamond-bearing stone “Hypatia” from southwest Egypt: A contribution to the debate on its origin

The stone named “Hypatia” found in the Libyan Desert Glass area of southwest Egypt is carbon-dominated and rich in microdiamonds. Previous noble gas and nitrogen isotope studies suggest an extraterrestrial origin. We report on a reconnaissance study of the carbonaceous matrix of this stone and the phases enclosed in it. This focused on areas not affected by numerous transecting fractures mostly filled with secondary minerals. The work employed scanning electron microscopy (SEM) with energy-dispersive (EDS) and wavelength-dispersive (WDS) electron microprobe (EMPA) analysis, Proton Induced X-ray Emission (PIXE) spectrometry and micro-Raman spectroscopy. We found that carbonaceous matrices of two types occur irregularly intermingled on the 50–500 μm scale: Matrix-1, consisting of almost pure carbonaceous matter, and Matrix-2, containing Fe, Ni, P and S at abundances analyzable by microprobe. Matrix-2 contains the following phases as inclusions: (i) (Fe,Ni) sulphide occurring in cloud-like concentrations of sub-μm grains, in domains of the matrix that are enriched in Fe and S. These domains have (Fe + Ni)/S (atomic) = 1.51 ± 0.24 and Ni/Fe = 0.086 ± 0.061 (both 1SD); (ii) grains up to ∼5 μm in size of moissanite (SiC); (iii) Ni-phosphide compound grains up to 60 μm across that appear cryptocrystalline or amorphous and have (Ni + Fe)/P (atomic) = 5.6. ± 1.7 and Ni/Fe = 74 ± 29 (both 1SD), where both these ratios are much higher than any known Ni-phosphide minerals; (iv) rare grains (observed only once) of graphite, metallic Al, Fe and Ag, and a phase consisting of Ag, P and I. In Matrix-2, Raman spectroscopy shows a prominent narrow diamond band at 1340 cm−1. In Matrix-1 the D and G bands of disordered carbon are dominant, but a minor diamond band is ubiquitous, accounting for the uniform hardness of the material. The D and G bands have average full width at half maximum (FWHM) values of 295 ± 19 and 115 ± 19 cm−1, respectively, and the D/G intensity ratio is 0.75 ± 0.09 (both 1SD). These values are similar to those of the most primitive solar system carbonaceous matter. The diamond phase is considered to be a product of shock. The (Fe, Ni) sulphide phase is probably pyrrhotite and a shock origin is likewise proposed for it. Moissanite is frequently associated with the Ni-phosphide phase, and a presolar origin for both is suggested. The lack of recrystallization of the Ni-phosphide phase suggests that the Hypatia stone did not experience long-lasting thermal metamorphism, in accord with the Raman D-G band characteristics.A lack of silicate matter sets the stone apart from interplanetary dust particles and known cometary material. This, along with the dual intermingled matrices internal to it, could indicate a high degree of heterogeneity in the early solar nebula.

Reconstructing the Firing and Pigment Processing Technologies of Corinthian Polychrome Ceramics, 8-6th Centuries B.C.E

ABSTRACTDecorative, polychrome ceramics from Corinth, Greece, produced during the 8th-6th centuries B.C.E. were luxury goods widely traded throughout Greece and the Mediterranean. Corinthian pottery is the first 5-color polychrome ceramic technology, having slip-glazes in distinctive white, black, red, yellow, and purple colors, and in a variety of surface finishes from glossy, to semi-matte, to matte. The firing temperature range, 925-1075°C, was determined experimentally to be to be higher than previously reported, similar to the Corinthian amphorae and other ceramic products. This firing range is higher than that of the better known, more prestigious Athenian Black-figure and Red-figure ceramics. In this study three examples of Corinthian and one example of Athenian Black-figure ceramics from the Marie Farnsworth collection at the University of Arizona were tested and compared to thirteen clays from Corinth. Analytical techniques included Fourier-transform infrared spectroscopy (FTIR), scanning-electron microscopy with energy-dispersive spectroscopy (SEM-EDS), micro-Raman spectroscopy, and wavelength-dispersive electron microprobe (EPMA with BSE-SEM).Artisans in Corinthian workshops experimented to change the colors of the slips by varying the type and amount of iron-rich raw material, as well as the composition of the clay used as a binder and the amount of flux used as a sintering aid to promote glass formation. Corinthian artisans developed not only different recipes to produce the various colors, but also they were able to control raw-material particle size and composition to produce variations in surface luster (matte, semi-matte and glossy). This research suggests that Corinthian polychrome-slip technology was based on careful control of particle processing, of compositional control of raw materials and their admixtures, and of firing temperature. The behavior or practice of adding different ratios of pigments and glass-forming fluxes to form various optical effects implies a detailed knowledge of what happens when these are heated and fired. This is a process of experimentation focused on developing a distinctive craft practice, which produced a distinctive and highly valued material. The Corinthians developed a more complex, easily recognizable, and culturally distinctive ceramic technology that was intentionally established as a cultural brand, and probably as a luxury brand of high socio-economic value. This research deepens our understanding of the complex pigment processing and firing technologies employed in the production of Corinthian ceramics.

First integrated tephrochronological record for the last ∼190 kyr from the Fucino Quaternary lacustrine succession, central Italy

We present the first integrated tephrochronological study (major and trace elemental glass composition, Sr and Nd isotope analyses, and 40Ar/39Ar dating) for the last one tenth (∼82 m) of the ∼900 m-thick Quaternary lacustrine succession of the Fucino Basin, the largest and probably only Central Apennine intermountain tectonic depression that hosts a continuous lacustrine succession documenting the Plio-Quaternary sedimentary history up to historical times. Major element glass compositions, determined using a wavelength-dispersive electron microprobe (WDS-EMPA), yielded the geochemical fingerprinting needed for a reliable identification of most of the 23 stratigraphically ordered tephra layers under investigation. These include tephra from Italian volcanoes such as Campi Flegrei, Etna, Colli Albani, Ischia, Vico, Sabatini, and undefined volcanic sources in the Neapolitan area and Latium region. The recognition of key Mediterranean marker tephra layers (e.g. X-5 and X-6) is supported by trace element data acquired by Laser Ablation Inductively Couple Plasma Mass Spectrometry (LA-ICP-MS). The Sr and Nd isotope compositions of selected layers where also determined for circumscribing the volcanic source of distal tephra and for supporting correlations with individual eruptive units. We also propose a new, more expeditious covariation diagram (CaO/FeOtot vs Cl) for identifying the volcanic source of trachytic to phonolitic and tephrytic to phonolitic tephra, that are the most common compositions of pyroclastic rocks from volcanoes of Campania and Latium regions. Finally, we present five new 40Ar/39Ar age determinations, including a new, analytically well-supported, and more precise 40Ar/39Ar age for the widespread Y-7 tephra, and the first 40Ar/39Ar age determinations for one tephra from the Sabatini volcanic district (∼126 ka) and one tephra from Neapolitan volcanic area (Campi Flegrei?; ∼159 ka). These newly dated tephra are widely dispersed (e.g. Monticchio, southern Italy, Adriatic Sea and Lake Ohrid, Macedonia-Abania) and have thus the potential to become important Mediterranean MIS 5 and MIS 6 tephrochronological markers. Altogether the new geochemical data and 40Ar/39Ar ages precisely constrain the chronology of the investigated Fucino succession spanning the last ∼190 ka. In light of these results and by considering that this sedimentary succession possibly extends back to ∼2 Ma, Fucino is likely to provide a very long, continuous tephrostratigraphic record for the Mediterranean area and become a key node in the dense network of tephra correlations of this region.

Mechanical Properties, Quantum Mechanical Calculations, and Crystallographic/Spectroscopic Characterization of GaNbO4, Ga(Ta,Nb)O4, and GaTaO4.

Single crystals as well as polycrystalline samples of GaNbO4, Ga(Ta,Nb)O4, and GaTaO4 were grown from the melt and by solid-state reactions, respectively, at various temperatures between 1698 and 1983 K. The chemical composition of the crystals was confirmed by wavelength-dispersive electron microprobe analysis, and the crystal structures were determined by single-crystal X-ray diffraction. In addition, a high-P-T synthesis of GaNbO4 was performed at a pressure of 2 GPa and a temperature of 1273 K. Raman spectroscopy of all compounds as well as Rietveld refinement analysis of the powder X-ray diffraction pattern of GaNbO4 were carried out to complement the structural investigations. Density functional theory (DFT) calculations enabled the assignment of the Raman bands to specific vibrational modes within the structure of GaNbO4. To determine the hardness (H) and elastic moduli (E) of the compounds, nanoindentation experiments have been performed with a Berkovich diamond indenter tip. Analyses of the load-displacement curves resulted in a high hardness of H = 11.9 ± 0.6 GPa and a reduced elastic modulus of Er = 202 ± 9 GPa for GaTaO4. GaNbO4 showed a lower hardness of H = 9.6 ± 0.5 GPa and a reduced elastic modulus of Er = 168 ± 5 GPa. Spectroscopic ellipsometry of the polished GaTa0.5Nb0.5O4 ceramic sample was employed for the determination of the optical constants n and k. GaTa0.5Nb0.5O4 exhibits a high average refractive index of nD = 2.20, at λ = 589 nm. Furthermore, in situ high-temperature powder X-ray diffraction experiments enabled the study of the thermal expansion tensors of GaTaO4 and GaNbO4, as well as the ability to relate them with structural features.

The Technological Development of Decorated Corinthian Pottery, 8th to 6th Centuries BCE

ABSTRACTPolychrome slipped and decorated pottery from Corinth, Greece, developed over two centuries from monochrome, dark brown slips and washes on a calcareous yellow clay body to a wide range of decorative techniques. Once significant experimentation with color variability began, five colors, each with various levels of gloss, were produced. Some slip colors involve multiple-step processing to control glass content and degree of sintering; the control of particle size to produce variable roughness and a matte or semi-matt or glossy appearance. Considerable evidence supports nearly continuous development and engineering of the ceramic slips, although no data support the improvement in composition or processing of the ceramic bodies. For instance, significant macro-porosity consistently is present in the bodies. We present the results of study of 27 sherds with 59 examples of Corinthian polychrome paint layers, measuring 5 to 35 microns in thickness, that were collected by Marie Farnsworth in the late 1950s and 1960s from Greek archaeological sites. Black, red, white, wine red (or purple) and overlying, matte banded slips and paints were studied by optical microscopy, petrographic and scanning-electron microscopy with semi-quantative energy dispersive x-ray analysis, as well as wavelength-dispersive electron microprobe (EPMA) elemental mapping and analysis.

Assessing dorsal scute microchemistry for reconstruction of shortnose sturgeon life histories

The imperiled status of sturgeons worldwide places priority on the identification and protection of critical habitats. We assessed the micro-structural and micro-chemical scope for a novel calcified structure, dorsal scutes, to be used for reconstruction of past habitat use and group separation in shortnose sturgeon (Acipenser brevirostrum). Dorsal scutes contained a dual-layered structure composed of a thin multi-layered translucent zone lying dorsally above a thicker multi-layered zone. Banding in the thick multi-layered zone correlated strongly with pectoral fin spine annuli supporting the presence of chronological structuring that could contain a chemical record of past environmental exposure. Trace element profiles (Sr:Ca), collected using both wavelength dispersive electron microprobe analysis and laser ablation inductively coupled mass spectrometry, suggest scutes record elemental information useful for tracing transitions between freshwater and marine environments. Moreover, mirror-image like Sr:Ca profiles were observed across the dual-zone structuring of the scute that may indicate duplication of the microchemical profile in a single structure. Additional element:calcium ratios measured in natal regions of dorsal scutes (Ba:Ca, Mg:Ca) suggest the potential for further refinement of techniques for identification of river systems of natal origin. In combination, our results provide proof of concept that dorsal scutes possess the necessary properties to be used as structures for reconstructions of past habitat use in sturgeons. Importantly, scutes may be collected non-lethally and with less injury than current structures, like otoliths and fin spines, affording an opportunity for broader application of microchemical techniques.

Redefinition of thalénite-(Y) and discreditation of fluorthalénite-(Y): A re-investigation of type material from the Österby pegmatite, Dalarna, Sweden, and from additional localities

AbstractUsing type material from the Österby pegmatite in Dalarna, Sweden, the chemical composition and structural parameters of thalénite-(Y) [ideally Y3Si3O10(OH)] were examined by wavelength dispersive spectroscopy electron microprobe (WDS EMP) analysis and single-crystal X-ray diffraction. High contrast back-scatter electron images of the Österby material show at least two generations of thalénite-(Y). The formula of the primary thalénite-(Y) normalized to 11 anions is (Y2.58Dy0.11Yb0.09Gd0.06Er0.06Ho0.02Sm0.02Tb0.02Lu0.02Nd0.01Tm0.01)Σ3.00Si3.01O10F0.97OH0.03. The secondary thalénite-(Y), replacing the primary material, is weakly enhanced in Y and depleted in the lightest and the heaviest rare-earth elements, yielding the formula (Y2.63Dy0.12Yb0.06Gd0.06Er0.05Ho0.02Sm0.02Tb0.02Tm0.01Nd0.01Lu0.01)Σ3.00Si3.01O10F0.98OH0.02. Structural data for thalénite-(Y) from Österby clearly indicate the monoclinic space group P21/n, with a = 7.3464(4), b = 11.1726(5), c = 10.4180(5) Å, β = 97.318(4)°, V = 848.13(7) Å3, Z = 4, which is consistent with previous investigations. The structure was refined from single-crystal X-ray diffraction data to R1 = 0.0371 for 1503 unique observed reflections, and the final chemical composition obtained from the refinement, (Y2.64Dy0.36)Σ3.00F0.987[Si3O10], Z = 4, is in good agreement with the empirical formula resulting from electron microprobe (EMP) analysis. Both techniques reveal a strong dominance of F over OH, which means that the type material actually corresponds to the fluorine analogue. Moreover, new EMP analyses of samples of thalénite-(Y) from an additional seven localities (Åskagen and Reunavare in Sweden; White Cloud and Snow Flake in Colorado, USA; the Guy Hazel claim in Arizona, USA; Suishoyama and Souri in Japan) clearly show the prevalence of F over OH as well. Based on these observations, the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association has recommended a redefinition of the chemical composition of thalénite-(Y) to represent the F-dominant species with the ideal formula Y3Si3O10F, as it has historical priority. Consequently, the later described fluorthalénite-(Y) has to be discredited.

Waimirite-(Y), orthorhombic YF3, a new mineral from the Pitinga mine, Presidente Figueiredo, Amazonas, Brazil and from Jabal Tawlah, Saudi Arabia: description and crystal structure

AbstractWaimirite-(Y) (IMA 2013-108), orthorhombic YF3, occurs associated with halloysite, in hydrothermal veins (up to 30 mm thick) cross-cutting the albite-enriched facies of the A-type Madeira granite (∼1820 Ma), at the Pitinga mine, Presidente Figueiredo Co., Amazonas State, Brazil. Minerals in the granite are 'K-feldspar', albite, quartz, riebeckite, 'biotite', muscovite, cryolite, zircon, polylithionite, cassiterite, pyrochlore-group minerals, 'columbite', thorite, native lead, hematite, galena, fluorite, xenotime-(Y), gagarinite-(Y), fluocerite-(Ce), genthelvite–helvite, topaz, 'illite', kaolinite and 'chlorite'. The mineral occurs as massive aggregates of platy crystals up to ∼1 μm in size. Forms are not determined, but synthetic YF3displays pinacoids, prisms and bipyramids. Colour: pale pink. Streak: white. Lustre: non-metallic. Transparent to translucent. Density (calc.) = 5.586 g/cm3using the empirical formula. Waimirite-(Y) is biaxial, meann= 1.54–1.56. The chemical composition is (average of 24 wavelength dispersive spectroscopy mode electron microprobe analyses, O calculated for charge balance): F 29.27, Ca 0.83, Y 37.25, La 0.19, Ce 0.30, Pr 0.15, Nd 0.65, Sm 0.74, Gd 1.86, Tb 0.78, Dy 8.06, Ho 1.85, Er 6.38, Tm 1.00, Yb 5.52, Lu 0.65, O (2.05), total (97.53) wt.%. The empirical formula (based on 1 cation) is (Y0.69Dy0.08Er0.06Yb0.05Ca0.03Gd0.02Ho0.02Nd0.01Sm0.01Tb0.01Tm0.01Lu0.01)Σ1.00[F2.54〈0.25O0.21]Σ3.00. Orthorhombic,Pnma,a= 6.386(1),b= 6.877(1),c= 4.401(1) Å,V= 193.28(7) Å3,Z= 4 (powder data). Powder X-ray diffraction (XRD) data [din Å (I) (hkl)]: 3.707 (26) (011), 3.623 (78) (101), 3.438 (99) (020), 3.205 (100) (111), 2.894 (59) (210), 1.937 (33) (131), 1.916 (24) (301), 1.862 (27) (230). The name is for the Waimiri-Atroari Indian people of Roraima and Amazonas. A second occurrence of waimirite-(Y) is described from the hydrothermally altered quartz-rich microgranite at Jabal Tawlah, Saudi Arabia. Electron microprobe analyses gave the empirical formula (Y0.79Dy0.08Er0.05Gd0.03Ho0.02Tb0.01Tm0.01Yb0.01)Σ1.00[F2.85O0.08〈0.07]Σ3.00. The crystal structure was determined with a single crystal from Saudi Arabia. Unit-cell parameters refined from single-crystal XRD data area= 6.38270(12),b= 6.86727(12),c= 4.39168(8) Å,V= 192.495(6) Å3,Z= 4. The refinement converged toR1= 0.0173 and wR2= 0.0388 for 193 independent reflections. Waimirite-(Y) is isomorphous with synthetic SmF3, HoF3and YbF3. The Y atom forms a 9-coordinated YF9tricapped trigonal prism in the crystal structure. The substitution of Y for Dy, as well as for other lanthanoids, causes no notable deviations in the crystallographic values, such as unit-cell parameters and interatomic distances, from those of pure YF3.

Age determination of nephrite by in-situ SIMS U–Pb dating syngenetic titanite: A case study of the nephrite deposit from Luanchuan, Henan, China

Nephrite is a kind of valuable jade which forms during metamorphism under greenschist facies conditions. Most investigations focus on the genesis of nephrite, however, the formation age of nephrite remains poorly constrained due to the lack of suitable dating methods. In this paper, the petrological, chemical characteristics, and mineral inclusions of nephrite collected from Luanchuan, Henan, China have been studied by optical and electron microscopy and wavelength-dispersive electron microprobe (EMP). The petrological observations show that nephrite consists mainly of tremolite, minor calcite and titanite, occasionally with rutile, quartz, serpentine, chlorite, pyrite, and apatite. The titanite and tremolite which are intergrown with each other share low-energy grain boundaries. It indicates that the two phases are equilibrated and can be considered as cogenetic. The chemical composition of tremolite is high in Si, Mg, Ca, but low in Fe, Cr, and Ni, which indicates that the nephrite from Luanchuan belongs to the dolomite type rather than the serpentinite type. The petrography of different nephrite structures suggests that the grain size of tremolite was determined by the stress intensity undergone during the nephrite formation progress. In-situ Secondary Ion Mass Spectrometer (SIMS) U–Pb dating of titanite from nephrite yielded an age of 361±4Ma, which is the first estimate for the time of formation of the Luanchuan nephrite deposit. This investigation provides a powerful in-situ dating method to unravel the age of nephrite, which could be served as a tool for future research on other nephrite deposits.

ON THE CRYSTAL-CHEMISTRY OF A NEAR-ENDMEMBER TRIPLITE, Mn2+2(PO4)F, FROM THE CODERA VALLEY (SONDRIO PROVINCE, CENTRAL ALPS, ITALY)

The crystal-chemistry of a near-endmember triplite, a manganese fluoro-phosphate [ideal chemical formula Mn2(PO4)F; a 12.109(2) A, b 6.5162(8) A, c 10.117(1) A, and β 106.16(2)°; space group I 2/ a ], from a granitic pegmatite exposed in the Codera Valley (Sondrio Province, Central Alps), has been investigated by means of wavelength dispersive electron-microprobe, infrared and Raman spectroscopies, and X-ray powder and single-crystal diffraction. Single-crystal anisotropic structure refinement gave a final agreement index R 1 = 0.0318 for 76 refined parameters and 1128 unique reflections with F o > 4σ( F o). The structure refinement of triplite from the Codera Valley confirms the topological features previously described both for a natural sample from Mica Lode (Colorado) and for the synthetic compound Mn2(PO4)F. The structure consists of isolated PO4 tetrahedra joined with distorted MO4F2 octahedra. The M(1) and M(2) octahedra share their edges to form chains; the chains of M(1) octahedra are parallel to [010], and those of M(2) are parallel to [100]. The analysis of the difference-Fourier maps of the electron density of triplite from the Codera Valley reveals a unique position for F, as reported in the literature for the OH-free synthetic Mn2(PO4)F. In contrast, two mutually exclusive F sites, with partial site occupancy, were reported in a previous structural study of OH-bearing triplite from Colorado (Mica Lode).

Comparative study of three sodium phosphates as corrosion inhibitors for steel reinforcements

A comparative study was performed on the inhibition of steel reinforcement corrosion using three soluble phosphates: sodium monofluorophosphate (Na2PO3F), disodium hydrogen phosphate (Na2HPO4) and trisodium phosphate (Na3PO4). Tests were carried out using ordinary Portland cement (OPC) paste specimens and OPC mortar specimens with embedded steel reinforcements. The corrosion inhibitors were deployed in two different ways: by immersion of OPC specimens in aqueous solutions containing the soluble phosphates (migrating corrosion inhibitor), and by addition of the phosphate powders to a fresh OPC paste (admixture corrosion inhibitor). After curing, the tested specimens were studied using X-ray diffraction, wavelength-dispersive electron microprobe analysis, linear polarisation resistance and electrochemical corrosion potential. A correlation was found between the phosphate content (by migration or admixture) in the OPC matrices and the steel corrosion rate.

The stained glass window of the southern transept of St. Anthony's Basilica (Padova, Italy): study of glasses and grisaille paint layers

This work reports results from a chemico-physical study of the stained glass window of the southern transept of St. Anthony's Basilica (Padova, Italy), dated to the late 19th century AD. Selected samples of glass with or without grisailles were characterised by means of various X-ray spectrometric techniques, such as wavelength dispersive X-ray fluorescence, electron microprobe, and scanning electron microscopy with energy dispersive X-ray microanalysis, coupled, in some cases, with X-ray powder diffraction. Integration of analytical results revealed many types of glass related to different phases of the “life” of stained glass, and the production technology of grisailles. In addition, the degree of damage undergone throughout the last century due to materials used in the production of windows was studied, to design and optimise a combined conservation and restoration strategy. Lastly, another important aim of the present study was to amplify the database on 19th-century stained glass windows, little documented in the literature.

Chemical composition of enamel and dentine in modern reptile teeth

AbstractElemental distribution maps by wavelength-dispersive electron microprobe of enamel and dentine in modern crocodile teeth illustrate variations in both minor and major elements. Mg has the largest difference between the enamel and dentine, being enriched in the dentine. Mg, Ca and P are not homogeneously distributed in the dentine, but their distribution reflects changes during growth of the teeth. These variations in compositional differences of teeth from modern samples potentially can assist in establishing growth rates in fossil teeth samples, and thereby provide information on the physiology of extant species.

M2B5 or M2B4? A Reinvestigation of the Mo/B and W/B System

AbstractThe literature states different compositions (M/B = 1:2 vs. 2:5) and structures for diborides of molybdenum and tungsten. Using X‐ray and neutron powder diffraction as well as energy and wavelength dispersive electron microprobe analysis, the Mo/B and W/B systems were now reinvestigated. Molybdenum diboride crystallizes as a stoichiometric compound Mo2B4 (formerly described as Mo2B5) in space group $R{\bar 3}m$ (No. 166, a, b = 3.01375(2) Å, c = 20.9541(3) Å), and as a non‐stoichiometric compound MoB2−x (formerly described as MoB2) in P6/mmm (No. 191, a, b = 3.043(2) Å, c = 3.067(2) Å), whereas stoichiometric tungsten diboride W2B4 (formerly described as W2B5) is found to crystallize in space group P63/mmc (No. 194, a, b = 2.9864(4) Å, c = 13.896(2) Å). These results seem to be supported by DFT calculations which show the instability of a hypothetic W2B5.

Deducing source rock lithology from detrital rutile geochemistry: An example from the Erzgebirge, Germany

This study evaluates the applicability of rutile trace element geochemistry to provenance studies. The study area is the Erzgebirge in eastern Germany, where metamorphic rocks ranging from lower greenschist facies conditions up to granulite facies conditions are exposed. We collected sand and rock samples from small catchment areas for a comparative analysis of rutile geochemistry using wavelength-dispersive electron microprobe. Our results show that rutile geochemistry is a powerful tool in provenance studies, allowing for the identification of source lithologies and an evaluation of the host orogen's metamorphic history. The log (Cr/Nb) ratio has proven to be decisive in discriminating between mafic and metapelitic lithologies. It is also useful for identifying different source rocks when plotted versus a third element or proxy. Furthermore, our results suggest that rutile thermometry can be applied to a much wider range of lithologies than previously assumed. A quantification of temperature populations within single sand samples shows that at high-grade metamorphic conditions, such as those found in the Erzgebirge, more than 65% of rutiles do not re-equilibrate during retrograde metamorphism and thus retain their peak temperature chemistry. Such samples, which have equilibrated at recent metamorphic conditions, can be identified by their 2- σ standard deviations of less than 120 °C. Below 550–600 °C, no complete equilibration is reached. Rutiles from greenschist facies and lower metamorphic conditions in the Erzgebirge still inherit relict temperatures from a former metamorphic cycle. They partly record very high temperatures > 950 °C and supposedly derive from erosion of the west African craton in Ordovician time.

Laser microprobe (U–Th)/He geochronology

A new analytical method had been developed to enable high-spatial-resolution (U–Th)/He dating of accessory minerals. It involves the use of a focused ArF excimer to ablate pits in a polished grain surface, with the evolved gases spiked for isotope-dilution measurement of radiogenic 4He. These data are converted to concentrations by precise measurement of each pit using an optical interferometric microscope. U, Th, and Sm concentration measurements are made using one of several alternative microanalytical techniques (e.g., wavelength-dispersive electron microprobe analysis or laser-ablation, inductively coupled plasma mass spectrometry). By way of illustration, we present both conventional and laser microprobe (U–Th)/He dating results for a Brazilian monazite sample. Laser microprobe data (28 measurements on two crystal fragments) yield a weighted mean (U–Th)/He date of 455.3 ± 3.7 Ma (2SE). This result is statistically indistinguishable from the mean conventional (U–Th)/He date for three separate grain fragments: 449.6 ± 9.8 Ma (2SE). The agreement of conventional and laser ablation dates should encourage a wide variety of applications of the technique, including: (1) detrital mineral dating for provenance and unroofing studies; (2) the dating of broken, included, highly zoned, or irregular grains which are not easily corrected for α-ejection; and (3) measuring 4He loss profiles that can be inverted to determine cooling histories.

Archaeometric analyses of game counters from Pompeii

Abstract Among the glass finds of the Pompeii excavations, numerous objects of opaque and transparent glassy material of different colours were recovered and classified as game counters. The main aims of this work were to characterize these samples so as to identify the materials used as colorants and opacifying agents, and subsequently to deduce the technology used for their production. The results of the chemical and mineralogical analyses obtained for game counters were also compared with those obtained for transparent and opaque glass artefacts. The chemical analyses were carried out, using only 300 mg of sample, by both wavelength-dispersive electron microprobe and X-ray fluorescence analysis. The crystalline phases present in the opaque glass were identified using both an automatic X-ray powder diffractometer and a Gandolfi camera. Secondary and backscattered electron images were obtained to study the distribution and morphology of the opacifier particles, and qualitative chemical analyses were obtained with an energy-dispersive system. All the game counters analysed can be classified as silica-soda-lime glass. Two calcium antimonates (CaSb 2 O 6 and Ca 2 Sb 2 O 7 ) were identified in the opaque white, green and blue glass, and Pb 2 Sb 2 O 7 particles were detected in the opaque yellow glass. Particles of metallic copper were detected by both energy-dispersive system and X-ray powder diffraction. These results support the hypothesis that transparent game counters were obtained by remelting of fragments of common transparent artefacts. In contrast, opaque finds were probably produced using the glassy paste employed in the production of mosaic tesserae.

A nonlethal approach using strontium in scales to distinguish periods of marine and freshwater residency of anadromous species

Spatiotemporal migration patterns of brook trout (Salvelinus fontinalis) and various other anadromous fish are poorly understood in many rivers of North America. A new, nonlethal approach to investigate these movements using analysis of scale microchemistry was developed that is relatively simple, cost effective, and potentially more accurate than other monitoring techniques. As fish grow, their scales incorporate in the calcified matrix different concentrations of trace elements present in ambient waters. Seawater Sr concentrations are 10–100 times higher compared with fresh water; thus, a higher Sr/Ca ratio in circulii corresponding to periods of life in seawater would be predicted. We used a wavelength-dispersive X-ray electron microprobe to assess Sr/Ca ratios along sagittal cross sections of scales, spanning the life history of a fish. We demonstrate that existing wavelength-dispersive X-ray electron microprobe studies using Sr analysis may suffer inaccuracies related to scale surface topography, and using the alternative embedding and cutting technique increases significantly the precision of Sr/Ca readings.