Clay Minerals – Forthcoming Special Issues

Extraterrestrial Clays

Clay Minerals is inviting contributions for a special collection entitled “Extraterrestrial clays”. The collection will comprise of articles on clays and associated minerals on Mars, meteorites, and any other extraterrestrial body.
The contributions may be of different types:

Articles that discuss existing interpretation problems, critically review previous interpretations, set forward some new idea or provide a perspective view of clays in other Solar System bodies and Earth. These are not necessarily review papers, but more focused contributions discussing specific aspects.

  • Research papers with novel data.
  • Research papers on the clay aspects of published work.

 The deadline for submission is 15 October 2021.
Javier Cuadros
Associate Editor

Advances in stevensite research

Stevensite is a trioctahedral smectite with structural formula (Ca0.5,Na)x(Mg,Fe2+3-x □x) Si4O10(OH)2•nH2O. The negative layer charge of stevensite is due to octahedral vacancies rather than substitutions in the lattice. Stevensite, has excellent adsorption properties compared to other smectites frequently used in the industry like montmorillonite. These properties stem from the negative layer charge which render stevensite a suitable adsorbent for positively charged ions and molecules and for polar organic compounds.
There are few stevensite deposits worldwide. Stevensite deposits have been described in central Spain, in New Jersey, USA and in Fés-Boulemane region, Morocco, known as rhassoul or ghassoul clay. The adsorption properties of the rhassoul clay have been investigated in the past and very good adsorption of heavy metals and organic molecules was determined. This special issue of of Clay Minerals is dedicated to the geology and mineralogy of stevensite deposits and the physical and chemical properties of this very interesting mineral.

Deadline for submissions: 15 November 2021
Associate Editor: Miroslav Pospíšil

Significance of ion-adsorption (IA) type clay deposits as potential sources of lanthanides (REE)+Y+Sc

REE (lanthanides)+Y+Sc are essential for high-technology industries and they are also high-ranking critical metals for low-carbon energy technologies. However, being rare metals, they have significant supply risk as opposed to their economic and environmental importance. Recently, IA type clay deposits, in which REE occurred adsorbed onto clay mineral surfaces gained importance as potential economic sources of these elements. They can be recovered with high extraction yields by using the concept of ion-exchange mechanism. Geologically, REE -IA clay deposits form as supergene enrichment metal deposit formed by weathering of granitic, mafic/ultramafic, sedimentary and tuffaceous bedrocks as a consequence of intensive lateritic/ hydrothermal alteration of primary minerals and formation of mainly kaolinitic, smectitic, bauxitic and iron-oxide rich clay deposits.
This Special Issue of Clay Minerals will attract the interests of scientists who study:
1. The geology, origin and factors controlling the distribution (in time and space) of REE -IA clay deposits,
2. Their overall mineralogical, crystal- chemical and geochemical characteristics,
3. Geochemistry of groundwaters, effects of organic acids, plants and microbiol processes on the formation of REE-IA clay deposits (in the Critical Zone),
4. Paleoclimatologic implications of IA type of paleosols,
5. The mechanism(s) of adsorption processes of REE occurring on the solid surfaces of clay minerals (considering e.g. electrical double layer and ion-exchange mechanisms),
6. Metal mining and extraction methods of REE from IA clays.

Deadline for submissions: 31 December 2021
Guest Associate Editor: Asuman Günal Türkmenoğlu