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Iowaite, a re-investigation

  • R. S. W. Braithwaite (a1), P. J. Dunn (a2), R. G. Pritchard (a1) and W. H. Paar (a3)


Iowaite has been re-examined using new, well crystallized material from the Palabora open pit mine, Transvaal. Microprobe, carbon analyser and thermal analyses, powder and single-crystal X-ray diffraction, infrared, UV-visible and mass spectroscopic and optical studies were made. The ideal formula is (OH)16Cl2·4H2O. It is trigonal, Rm, a = 3.1183(9), c = 24.113(8) Å, V = 203.1(2) Å3, Z = 3/8; D obs 2.09 g/cm3.; D calc 2.04 g/cm3; hardness (Mohs)=2 1/2. The interlayer Cl ions are displaced from the threefold axis. It is uniaxial negative, with ω = 1.561 ± 0.002, ε = 1.543 ± 0.002; coloured crystals are intensely pleochroic, due to intervalence charge transfer between the Fe3+ and Fe2+ substituting for Mg2+, with O pale yellow, E deep blue-green.



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Iowaite, a re-investigation

  • R. S. W. Braithwaite (a1), P. J. Dunn (a2), R. G. Pritchard (a1) and W. H. Paar (a3)


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