Petrological and geochemical classification of laterites

In this classifiation of lateritic coversfour major types are distinguished. ferricretes, latosols, conakrytes and bamites. In ferricretes, hematite is associated with kaolinite,$ming mottles, nodules and metanoduks. When, at the top ofpro-jks, goethite and sometimes gibbsite develop at the expense of hematite and kaolinite, protopisolitic andpisolitic dis-mantlingfacies are f inned FerriCretes, in which hematite and kaolinite firm concretions, are widespread and are the most common iron accumulations. Latosols are so) lateritic covers with a microglaebular structure. Red latosols, like ferricretes, are essentially formed by an assoriation of hematite and kaolinite, but with largerproportions ofgoethite and with the presence ofgibbsite. Lateritic bauxites are concentrations of aluminium with which iron is very ofen associated Four major types of later-itic bauxites: protobauxites, orthobamites, metabauxites and cryptobauxites are defined ar a finction of the nature of iron and aluminium minerals as well as their relative distributions in projks. Protobauxites are lateritic soils wheregibbsite andgoethite f i rm together under very humid climates. Orthobauxites are allites or arferrites, rich in gibbsite and red in colour, which do not exhibit a concretionary structure. Iron may be con-centrated in bard caps calledconakrytes and located close to the top of the bauxiticprojks. Conakrytes are reticular and non nodularferriies orferrallites in which hematite andgoethite dominate and where gibbsite could be present in small