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Abstract--Synthetic aluminous hematites and goethites have been examined by Fourier-transform infrared spectroscopy. For aluminous hematites prepared at 950~ a linear relationship exists between AI content and the location of the band near 470 cm ~, up to 10 mole % AI substitution which is shown to be the solubility limit. The spectra of aluminous goethites prepared in two different ways are qualitatively similar to each other, but differ as to the relationship between the position of the band near 900 cm -1 and the A1 content. The spectra of the two series of hematites produced by calcining the goethites at 590~ also show a strong dependence of band position and intensity on the goethite preparative method.

Abstract--57Fe M6ssbauer spectra of a cleaned Weipa, Australia, kaolin showed that a considerable fraction of the structural iron exhibits paramagnetic relaxation between 4~ and 300~ the first time that this has been observed for ferric ions in a mineral. The sample also contained a very fine particle ferric oxide/oxyhydroxide phase, probably of secondary origin.

Abstract--57Fe M6ssbauer spectra have been used to interpret the effects of different cleaning processes on the iron mineralogy of a Weipa, Australia, kaolin. A magnetically separated fraction contained 28% of its iron as hematite likely of secondary origin. An initial centrifugal size separation was shown to give an improved final product, and oxalic acid was found to be more efficient at removing Fe from the kaolinite surface than dithionite bleach. The MSssbauer spectra clearly show that beneficiation steps which give a substantial increase in kaolin brightness result in only minor changes in the clay iron mineralogy. Similar results were also obtained for two commercially available kaolins.