Silver isotopic composition

Woodland, S.J., Rebkamper, M., Halbday, A.N., Lee, D.-C., Hattendorf, B., and Giinfher, D. (2005) Accurate measmement of silver isotopic compositions in geological materials including low Pd/Ag meteorites. Geochim. Cosmochim. Acta, 69, 2153-2163. 

Chen JH, Wasserburg GJ (1983) The isotopic composition of silver and lead in two iron meteorites Cape York and Grant. Geochim Cosmochim Acta 47 1725-1737... 

In the case of lead arsenate (acid form), calcium arsenate, and sodium arsenate, the Pb-isotopic compositions closely match those of sulfides from porphyry copper deposits from southeastern Arizona, specifically from the Pima and Silver Bell districts (Bouse et al., 1999). Notably, other major historical producers of arsenic trioxide (e.g., Anaconda Copper Co., US Smelting Co., Jardine Mining Co.) used... 

Certain ore deposits may partially overlap in their lead isotope composition. In such a case, it might not be possible to decide on the basis of the lead isotope data alone which of the ore deposits in question provided the ore for metal artifacts that have lead isotope compositions that fall into the overlapping space. Sometimes, one of these ore deposits can be ruled out by using trace element data, particularly from gold and silver analyses (6). Lead isotope analyses by themselves can make a negative statement with absolute certainty in a way which chemical analysis can never hope to do. If the lead isotope composition of an artifact falls well outside the lead isotope field characteristic of a particular ore deposit then it is certain that the metal... 

Figure 5. Lead isotope compositions of Early Cycladic lead and silver artifacts.

Some of the objects from Kastri falling in Trojan field B need further discussion. Four of these objects (16167, 16169, 16171, and 16174) have lead isotope compositions that resemble the fingerprint of Cypriot copper ores however, we have rejected the hypothesis that these metal objects at Kastri are Cypriot in origin by comparing their trace elemental composition, particularly gold and silver content, with some Cypriot copper artifacts excavated on Cyprus. The results of the neutron activation analyses of these objects are presented in Figure 11. 

Figure 11. Gold and silver concentrations for objects from Kastri on Syros with Cypriot lead isotope composition compared with the gold and silver content of Cypriot artifacts. (Reproduced with permission from ref. 6. Copyright 1984 Basil Blackwell Publisher, Ltd.)...

Only a few publications have been devoted to the kinetic isotope effects in the decomposition of formic acid, and only the metals Ag and Au were investigated. The most extensive work was published by Block and Krai (21), who measured the rate of the decomposition of formic acid over silver wires between 190 and 250°C, using the isotopic compositions HCOOH, HCOOD, DCOOH, and DCOOD. The kinetic isotope effect a, which is defined as the number of times the reaction... 

The oxo-anion PO4 is a key constituent in the Earth s biosphere. Recently, oxygen isotope fractionations (both equilibrium and kinetic) have been measured experimentally between orthophosphate ion H2PO4 and H2O from 50 to 135°C by Lecuyer et al. (1999). They controlled the experimental conditions such that H2PO4 was the dominant species in solution (pH 5 at ambient conditions). They measured both the oxygen isotope composition of the H2O and the dissolved phosphate (by precipitation as silver phosphate), and fit the time series data to a simple first order expression similar to Equation (87), where... 

Lead is an impurity in silver. The isotopic composition of the lead measured by inductively coupled plasma-mass spectrometry provides evidence for the origin of the silver because silver mined in each region retains the pattern of lead isotopes from that region. 

Nine of ten ornaments found at Allahdino have a lead isotope composition similar to that of silver-containing lead ore from South Balochistan (Figure 20-20), which is near Allahdino. Five ornaments from Mohenjo-daro and one of ten from Allahdino do not match any known mining sites in Pakistan but are similar in isotopic composition to ore from South Rajasthan in India and a site across the Arabian Sea in Oman. It is possible that the silver came from these more distant sites. Archaeologists make increasing use of the most sophisticated analytical techniques to address question in anthropology. 

Kaiser, T. and Wasserburg, G.J. (1983) The isotopic composition and concentration of Ag in iron meteorites and the origin of exotic silver. Geochim. Cosmochim. Acta, 47, 43-58. 

The ultimate question behind all calibration chains is how one can establish accurate isotopic composition of the enriched isotope materials with suitable precision. The measurements of the isotope amount ratio of the enriched materials, soon-to-be cahbrators, initially cannot be calibrated. In a simplified example, the calibration can be done if the mass bias is identical when measuring both materials and their mixture [23]. Consider the silver system, N( Ag)/N( Ag), and measurements of three isotope amount ratios (i) of silver enriched in Ag (ta), (ii) of silver enriched in ° Ag (tb), and (iii) of the mixture of both of these materials (tmix) If the chemical purity of both materials is known and the mass bias remains the same in all measurements, then the isotopic composition of both enriched materials can be obtained from the following three equations ... 

ICP-MS has also been used to measure trace elements in archaeological native silver artifacts [345] in order to identify their geographical origins. The low detection limits provided by ICP-MS allowed analysis of trace elements on 3 to 15 mg of sample. The passivation of alloy steels using acid solutions has been studied by XPS measurements of the solid in combination of ICP-MS analysis of the passivation solutions [346,347]. When bullets are crushed on impact, striations cannot be used for identification. The percentage of antimony, trace element composition, and lead isotope ratios in bullets was measured for forensic evidence [348]. The lead isotope ratios were found to be the most useful evidence. 

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