scholarly journals Silver isotope and volatile trace element systematics in galena samples from the Iberian Peninsula and the quest for silver sources of Roman coinage

Geology ◽  
2021 ◽  
Author(s):  
Jean Milot ◽  
Janne Blichert-Toft ◽  
Mariano Ayarzagüena Sanz ◽  
Chloé Malod-Dognin
Keyword(s):  
Trace Elements ◽  
Low Temperature ◽  
Iberian Peninsula ◽  
Isotopic Fractionation ◽  
Upper Crust ◽  
Isotopic Compositions ◽  
Roman Coins ◽  
Isotopic Abundances ◽  
Best Fit ◽  
Silver Isotope

Silver played a key role in the progressive monetization of early Mediterranean civilizations. We combine Pb and Ag isotopes with volatile trace elements (Bi, Sb, and As) to assess whether, during the Roman occupation of Iberia, galena constituted a significant source of silver. We find that the Pb and Ag isotopic compositions of 47 samples of galena from eight different Iberian mining provinces, many of them exploited during Roman times, are uncorrelated. This indicates that their respective isotopic variabilities depend on different petrogenetic processes. Moreover, the range of Ag isotopic abundances is approximately six times wider than that displayed worldwide by silver coins in general and Roman silver coins in particular. Although galena from the Betics provides the best fit for Pb isotopes with Roman coins, their fit with Ag isotopic compositions is at best sporadic. We suggest that, together with Sb, Bi, and As, silver is primarily derived from fluids boiled off from differentiated mantle-derived magmas. These fluids, in turn, reacted with preexisting galena and functioned as a silver trap. Lead sulfides with ε109Ag of ~0 and unusually rich in Ag, Sb, Bi, and As were the most probable sources of ancient silver, whereas samples with ε109Ag departing significantly from ~0 reflect low-temperature isotopic fractionation processes in the upper crust.

scholarly journals Review of footnotes and annotations to the 1949–2013 tables of standard atomic weights and tables of isotopic compositions of the elements (IUPAC Technical Report)

2016 ◽  
Vol 88 (7) ◽  
pp. 689-699 ◽  
Author(s):  
Tyler B. Coplen ◽  
Norman E. Holden
Keyword(s):  
Isotopic Fractionation ◽  
Numerical Data ◽  
Atomic Weight ◽  
Current Standard ◽  
Additional Information ◽  
Isotopic Compositions ◽  
Technical Report ◽  
Isotopic Abundances ◽  
Terrestrial Material ◽  
A Current

Abstract The Commission on Isotopic Abundances and Atomic Weights uses annotations given in footnotes that are an integral part of the Tables of Standard Atomic Weights to alert users to the possibilities of quite extraordinary occurrences, as well as sources with abnormal atomic-weight values outside an otherwise acceptable range. The basic need for footnotes to the Standard Atomic Weights Table and equivalent annotations to the Table of Isotopic Compositions of the Elements arises from the necessity to provide users with information that is relevant to one or more elements, but that cannot be provided using numerical data in columns. Any desire to increase additional information conveyed by annotations to these Tables is tempered by the need to preserve a compact format and a style that can alert users, who would not be inclined to consult either the last full element-by-element review or the full text of a current Standard Atomic Weights of the Elements report. Since 1989, the footnotes of the Tables of Standard Atomic Weights and the annotations in column 5 of the Table of Isotopic Compositions of the Elements have been harmonized by use of three lowercase footnotes, “g”, “m”, and “r”, that signify geologically exceptionally specimens (“g”), modified isotopic compositions in material subjected to undisclosed or inadvertent isotopic fractionation (“m”), and the range in isotopic composition of normal terrestrial material prevents more precise atomic-weight value being given (“r”). As some elements are assigned intervals for their standard atomic-weight values (applies to 12 elements since 2009), footnotes “g” and “r” are no longer needed for these elements.

scholarly journals Searching for signatures of life on Mars: an Fe-isotope perspective

2006 ◽  
Vol 361 (1474) ◽  
pp. 1715-1720 ◽  
Author(s):  
M Anand ◽  
S.S Russell ◽  
R.L Blackhurst ◽  
M.M Grady
Keyword(s):  
Low Temperature ◽  
Liquid Water ◽  
Isotope Composition ◽  
Isotopic Fractionation ◽  
Isotope Ratios ◽  
Experimental Investigations ◽  
Form Of Life ◽  
Geological Past ◽  
Martian Meteorites ◽  
Fe Reduction

Recent spacecraft and lander missions to Mars have reinforced previous interpretations that Mars was a wet and warm planet in the geological past. The role of liquid water in shaping many of the surface features on Mars has long been recognized. Since the presence of liquid water is essential for survival of life, conditions on early Mars might have been more favourable for the emergence and evolution of life. Until a sample return mission to Mars, one of the ways of studying the past environmental conditions on Mars is through chemical and isotopic studies of Martian meteorites. Over 35 individual meteorite samples, believed to have originated on Mars, are now available for lab-based studies. Fe is a key element that is present in both primary and secondary minerals in the Martian meteorites. Fe-isotope ratios can be fractionated by low-temperature processes which includes biological activity. Experimental investigations of Fe reduction and oxidation by bacteria have produced large fractionation in Fe-isotope ratios. Hence, it is considered likely that if there is/were any form of life present on Mars then it might be possible to detect its signature by Fe-isotope studies of Martian meteorites. In the present study, we have analysed a number of Martian meteorites for their bulk-Fe-isotope composition. In addition, a set of terrestrial analogue material has also been analysed to compare the results and draw inferences. So far, our studies have not found any measurable Fe-isotopic fractionation in bulk Martian meteorites that can be ascribed to any low-temperature process operative on Mars.

Isotope-abundance variations of selected elements (IUPAC Technical Report)

2002 ◽  
Vol 74 (10) ◽  
pp. 1987-2017 ◽  
Author(s):  
Tyler B. Coplen ◽  
John Karl Böhlke ◽  
P. De Bièvre ◽  
T. Ding ◽  
N. E. Holden ◽  
...  
Keyword(s):  
Chemical Elements ◽  
Radioactive Decay ◽  
Atomic Weight ◽  
Chemical Fractionation ◽  
Isotope Abundance ◽  
Isotopic Compositions ◽  
Technical Report ◽  
Isotopic Abundances ◽  
Calcium Iron ◽  
Physical And Chemical

Documented variations in the isotopic compositions of some chemical elements are responsible for expanded uncertainties in the standard atomic weights published by the Commission on Atomic Weights and Isotopic Abundances of the International Union of Pure and Applied Chemistry. This report summarizes reported variations in the isotopic compositions of 20 elements that are due to physical and chemical fractionation processes (not due to radioactive decay) and their effects on the standard atomic-weight uncertainties. For 11 of those elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine, copper, and selenium), standard atomic-weight uncertainties have been assigned values that are substantially larger than analytical uncertainties because of common isotope-abundance variations in materials of natural terrestrial origin. For 2 elements (chromium and thallium), recently reported isotope-abundance variations potentially are large enough to result in future expansion of their atomic-weight uncertainties. For 7 elements (magnesium, calcium, iron, zinc, molybdenum, palladium, and tellurium), documented isotope variations in materials of natural ter- restrial origin are too small to have a significant effect on their standard atomic-weight uncertainties. This compilation indicates the extent to which the atomic weight of an element in a given material may differ from the standard atomic weight of the element. For most elements given above, data are graphically illustrated by a diagram in which the materials are specified in the ordinate and the compositional ranges are plotted along the abscissa in scales of (1) atomic weight, (2) mole fraction of a selected isotope, and (3) delta value of a selected isotope ratio.

Volatility of selected minor and trace elements in the low-temperature ash of an Illinois herrin no. 6 coal

Fuel ◽  
1980 ◽  
Vol 59 (11) ◽  
pp. 816-819
Author(s):  
Sheldon H.D. Lee ◽  
Irving Johnson ◽  
Jack Fischer
Keyword(s):  
Trace Elements ◽  
Low Temperature ◽  
Minor And Trace Elements

The chlorine-isotopic composition of lunar KREEP from magnesian-suite troctolite 76535

2020 ◽  
Vol 105 (8) ◽  
pp. 1270-1274
Author(s):  
Francis M. McCubbin ◽  
Jessica J. Barnes
Keyword(s):  
Isotopic Composition ◽  
Melt Inclusions ◽  
Melt Inclusion ◽  
Isotopic Fractionation ◽  
Magma Ocean ◽  
Geochemical Composition ◽  
Isotopic Compositions ◽  
Stable Isotopic ◽  
Lunar Samples

Abstract We conducted in situ Cl isotopic measurements of apatite within intercumulus regions and within a holocrystalline olivine-hosted melt inclusion in magnesian-suite troctolite 76535 from Apollo 17. These data were collected to place constraints on the Cl-isotopic composition of the last liquid to crystallize from the lunar magma ocean (i.e., urKREEP, named after its enrichments in incompatible lithophile trace elements like potassium, rare earth elements, and phosphorus). The apatite in the olivine-hosted melt inclusion and within the intercumulus regions of the sample yielded Cl-isotopic compositions of 28.3 ± 0.9‰ (2σ) and 30.3 ± 1.1‰ (2σ), respectively. The concordance of these values from both textural regimes we analyzed indicates that the Cl-isotopic composition of apatites in 76535 likely represents the Cl-isotopic composition of the KREEP-rich magnesian-suite magmas. Based on the age of 76535, these results imply that the KREEP reservoir attained a Cl-isotopic composition of 28–30‰ by at least 4.31 Ga, consistent with the onset of Cl-isotopic fractionation at the time of lunar magma ocean crystallization or shortly thereafter. Moreover, lunar samples that yield Cl-isotopic compositions higher than the value for KREEP are likely affected by secondary processes such as impacts and/or magmatic degassing. The presence of KREEP-rich olivine-hosted melt inclusions within one of the most pristine and ancient KREEP-rich rocks from the Moon provides a new opportunity to characterize the geochemistry of KREEP. In particular, a broader analysis of stable isotopic compositions of highly and moderately volatile elements could provide an unprecedented advancement in our characterization of the geochemical composition of the KREEP reservoir and of volatile-depletion processes during magma ocean crystallization, more broadly.

scholarly journals Alumina Extraction from Coal Fly Ash via Low-Temperature Potassium Bisulfate Calcination

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 585 ◽  
Author(s):  
Chunbin Guo ◽  
Jingjing Zou ◽  
Shuhua Ma ◽  
Jianlin Yang ◽  
Kehan Wang
Keyword(s):  
Fly Ash ◽  
Low Temperature ◽  
Extraction Efficiency ◽  
Coal Fly Ash ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Increasing Demand ◽  
Technology Effects ◽  
Best Fit

Owing to the depletion of bauxite and increasing demand for alumina, calcination methods for extracting alumina from coal fly ash (CFA) were developed. However, these methods have disadvantages such as the need for high temperatures and the emission of toxic gases. Hence, in this study, Al2O3 was extracted from CFA via low-temperature potassium bisulfate calcination technology. Effects of the potassium bisulfate amount, calcination temperature, and calcination time on the alumina extraction efficiency were investigated using X-ray diffraction, thermal gravimetry, scanning electron microscopy, differential scanning calorimetry, and energy-dispersive spectroscopy. It was found that this technique could recover alumina efficiently, and potassium bisulfate significantly contributed to the degradation of mullite and corundum phases. Al2O3 in CFA was converted into soluble K3Al(SO4)3. With a KHSO4/Al2O3 molar ratio of 7:1, calcining temperature of 230 °C, and calcining time of 3 h, the alumina extraction efficiency reached a maximum of 92.8%. The Avrami–Erofeev equation showed the best fit with the kinetic data for the low-temperature calcination of CFA with KHSO4. The activation energy was 28.36 kJ/mol.

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