The combination of X-ray diffractometry (XRD), diffuse reflectance spectroscopy (DRS) and isothermal remanent magnetization (IRM) was used to identify the mineralogy of laterites from southern Mali, consisting of a saprolite and a ferriferous duricrust. Quartz, gibbsite, kaolinite, and vanadian muscovite were detected by XRD. Comparison of DRS and IRM data indicated magnetite as the only ferrimagnetic phase. All goethites from the saprolite contained an Al-amount of approximately 14.7 mole% Al. In the duricrust, two types of goethites occurred, a pure one and one with an Al-substitution of 12.1 mole% as indicated by XRD and DRS. X-ray diffractometry revealed an Al-substitution in hematite of approximately 6.7 mole%, but no correlation between Al-substitution and band position in DRS was found. More calibration is necessary to improve the analysis of Al-substitution in natural hematite by DRS.
|Pages (de - à)||13-20|
|Nombre de pages||8|
|journal||Schweizerische Mineralogische und Petrographische Mitteilungen|
|Numéro de publication||1|
|Etat de la publication||Publié - 1 déc. 1997|