Copper isotope variability in acid ferric sulfate dissolution of natural djurleite (Cu1.94S)

S. E. Young, J. B. Hiskey, J. Ruiz

Research output: Contribution to conferencePaper

Abstract

The resurgence of interest in transition metal isotope chemistry is the result of improved instrument precision and sensitivity. This has been achieved using multiple collector inductively-coupled mass spectrometry (MC-ICPMS) which allows simultaneous measurement of several isotope ratios in low concentrations. Copper isotope investigations have benefited from this improved technology. This study has demonstrated that appreciable Cu isotope ratio variability accompanies progressive acid ferric sulfate leaching of natural djurleite, Cu1.94S. Copper-bearing solutions from early stages of reaction (less than 10% cumulative copper dissolution) are enriched in 65Cu (δ65Cu = 1.2 ± 0.04%) compared to the initial djurleite experimental feed material (δ65Cu = -0.05 ± 0.04%). With continued reaction, 65Cu of the copper solutions steadily decreases, approaching the isotopic value of the original djurleite. As Cu:S ratio of the remaining solid material decreases, mineralogy of the residuum progresses through a series of non-stoichiometric copper sulfide phases until reaching a kinetic barrier at about 44% copper dissolution. XRD analyses has verified that the mineralogy at this boundary is dominated by the mineral yarrowite, Cu 1.12S. From djurleite to yarrowite, the average Cu-S bond length increases, resulting in an increased proportion of 4-coordinated Cu-S polyhedra over 3-coordinated geometries. This trend suggests that Cu isotope fractionation may be linked to the preference of the heavier 65Cu isotope for the lower coordinated configuration.

Original languageEnglish (US)
Pages1346-1353
Number of pages8
StatePublished - Dec 1 2006
Event23rd International Mineral Processing Congress, IMPC 2006 - Istanbul, Turkey
Duration: Sep 3 2006Sep 8 2006

Other

Other23rd International Mineral Processing Congress, IMPC 2006
CountryTurkey
CityIstanbul
Period9/3/069/8/06

ASJC Scopus subject areas

  • Earth-Surface Processes

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    Young, S. E., Hiskey, J. B., & Ruiz, J. (2006). Copper isotope variability in acid ferric sulfate dissolution of natural djurleite (Cu1.94S). 1346-1353. Paper presented at 23rd International Mineral Processing Congress, IMPC 2006, Istanbul, Turkey.