Although most of the minerals composing clays are phyllosilicates, there are other materials which, based on their physical and colloidical properties such as plasticity, swallowing, hardening upon firing (according to the definition of AIPEA, 1995), belong to the group of clays.
These are mainly geological nanomaterials: poorly crystalline or amorphous (Fe-Mn) oxides - oxi-hydroxides and aluminosilicates. They are very common in soils and unconsolidated sediments, but they may occur in a wide range of geological environments including extraterrestrial ones as well. They can form coatings on other phyllosilicate grains and may result from microbiological and chemical interactions. In terrestrial environments, these materials are important Fe-bearing phases and can host significant (toxic) heavy metal contaminations.
However, as they are nanosized particles, their identification is not straightforward, their thorough and quantitative examination requires state of the art techniques. For the same reason, laboratory preparation methods and analytical techniques are of great importance.
This session provides an open platform to discuss the latest results on the research of these non-phyllosilicate clays.