Kationeita

Kationeita is a hypothetical mineral species introduced in mineralogical pedagogy to illustrate cation exchange processes in layered solids. It is not recognized as a naturally occurring mineral by major authorities.

The name combines “cation” with the mineral-name suffix -eita, following conventions such as -ite/-itea; used for teaching contexts.

Conceptually, kationeita is a layered aluminosilicate with a two-dimensional sheet of tetrahedrally coordinated cations linked to octahedral layers, forming interlayer galleries that host exchangeable cations. The interlayer cations (for example Na+, K+, Ca2+) can be readily exchanged with external aqueous solutions, while the framework remains intact. The exact composition is variable and left undefined in principle.

In pedagogical models, kationeita is described as having a soft, pale mineral with vitreous to pearly luster, Mohs hardness around 4–5, and a white to pale gray color in aggregated samples. Its density is model-dependent.

As a hypothetical example, it has no confirmed natural occurrence. Researchers often synthesize kationeita analogues in hydrothermal or solvothermal experiments to study cation selectivity and exchange kinetics.

The concept supports teaching about cation exchange capacity, selectivity sequences of different cations, hydration effects, and environmental geochemistry. It also serves as a placeholder in computational databases for simulation studies.