Kelsenin

Kelsenin is a fictional mineral used in geology education to illustrate concepts of mineral classification, crystallography, and chemical substitution in silicate networks. In most teaching formulations, Kelsenin is described as a blue monoclinic aluminosilicate with a layered tetrahedral framework and moderate hardness. It is not a naturally occurring mineral; rather, it appears in textbooks and classroom demonstrations as a hypothetical example to explore structure–property relationships.

Etymology and naming: The mineral is named in honor of the fictional mineralogist Dr. Kelsen, who is said to have proposed its characteristic structure and substitutions for instructional purposes. Typical formulations specify substitutions within the tetrahedral sheets, such as replacement of silicon by aluminum and of alkali metals by larger monovalent cations, to illustrate charge balance and framework distortion.

Educational role: Kelsenin serves as a controlled model for teaching crystal systems, coordination, cleavage, and optical properties. In exercises, students predict its cleavage directions, measure refractive index concepts, and discuss how substitutions affect stability and unit-cell parameters. Because it is fictional, Kelsenin helps avoid misinterpretation of real minerals while providing a consistent framework for problem-based learning in mineralogy courses.