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M$ouml$ssbauer study of Egyptian goethite

1974; Institute of Physics; Volume: 7; Issue: 15 Linguagem: Inglês

10.1088/0022-3727/7/15/317

1361-6463

N. A. Eissa, H. A. Sallam, S. Sh. Gomaa, S.A. Saleh, Z. Miligy,

Minerals Flotation and Separation Techniques

Mössbauer spectroscopy has been used for the study of Egyptian goethite from different deposits of the Bahariya Oasis, in order to identify the different iron forms in the ore, and to investigate the physical properties of the mineral and its changes according to the geochemical conditions under which the ore was formed. Four representative samples were selected: the first one showed the existence of haematite with goethite, which is the normal final form to which goethite is transformed under high temperatures; the second gave two internal magnetic fields which could be due to water excess; the third one showed a relaxation effect due to small particle size; the fourth gave an extra hyperfine pattern with negative isomer shift which is still under investigation. The results obtained were confirmed by the x-ray diffraction and thermal analysis. A synthetic sample of α-FeOOH has been measured for comparison, in the temperature range from 77 to 392 K (the Néel point).