Exchange of light rare earths for Ca in apatite |
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| Authors: | Abderrahmane Iqdari Bruce Velde Noureddine Benalioulhaj Saint-Clair Dujon Nacer El Yamine |
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| Institution: | 1. Département de géologie, faculté des sciences et techniques, BP 577 Settat, Maroc;2. Laboratoire de géologie, École normale supérieure, URA 1316 CNRS, 24, rue Lhomond, 75231 Paris cedex 05, France;3. Département de génie minéral, École Mohammadia des ingénieurs, BP 765, Agdal, Rabat, Maroc |
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| Abstract: | Diffusion experiments were carried out on natural apatite crystals that were immersed in molten light rare earth element (REE) chloride salt at temperatures between 900 and 1150 °C for periods up to 35 days. Electron microprobe analysis of the crystals showed that light REEs replaced Ca according to electronic balance, i.e. for . These diffusion profiles indicate that a maximum amount of substitution in the structure occurs when two of the ten Ca ions in apatite are replaced by the REE diffusing elements. Anisotropic diffusion is observed between a and c crystallographic directions. Comparison of maximum distance indicates that the larger ions move more easily in the apatite structure. We conclude that the light REEs diffuse within the channel structures of the mineral, and that this diffusion is controlled by the substitution type of elements in the calcium sites. To cite this article: A. Iqdari et al., C. R. Geoscience 335 (2003). |
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| Keywords: | rare-earth elements apatite diffusion terres rares apatite diffusion |
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