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Hyperfine Interactions

, Volume 84, Issue 1, pp 427–431 | Cite as

Characterization of natural chromite ((Mg,FeII)(Al,FeIIICr)2O4) samples from the Bushveld Complex, South Africa

  • J. Nell
  • H. Pollak
Article

Abstract

Fe3+/Fe2+ ratios were determined for a suite of chromite samples from the Bushveld Complex, South Africa, using57Fe Mössbauer spectroscopy and a ceric sulphate titration method. Two distinctly different types of chromite were identified. Type I chromites have low Fe3+/Fe2+ ratios (between 0.2 and 0.4), and contain 3 cations for every 4 oxygen ions in the chemical formula unit. Type II chromites, on the other hand, have Fe3+/Fe2+ ratios between 0.7 and 1.3, and contain considerably less than 3 cations per 4 oxygen ions in the formula unit. Type II chromites result from the oxidation of type I chromites and can be reduced back to the latter by heating in a gas mixture containing 1% CO and 99% CO2 at 1000 °C.

Keywords

Oxidation Oxygen Sulphate Spectroscopy Thin Film 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© J.C. Baltzer AG, Science Publishers 1994

Authors and Affiliations

  • J. Nell
    • 1
  • H. Pollak
    • 2
  1. 1.Mineralogy and Process Chemistry DivisionMintekRandburgSouth Africa
  2. 2.Department of PhysicsUniversity of the WitwatersrandJohannesburgSouth Africa

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