Kernellit

Kernellit is a hypothetical mineral species described in mineralogical literature as a potassium aluminum silicate within the framework silicate subgroup. It is chiefly used in teaching and theoretical discussions to illustrate crystal-chemical principles of the feldspar family and to demonstrate how framework silicates accommodate substitutions.

Proposed composition and structure: The ideal formula is written as KAlSi3O8 with trace amounts of Fe, Mg, or Na. The mineral is described as crystallizing in a monoclinic system with a quartz-like framework of corner-sharing SiO4 tetrahedra. Physical properties are reported as hardness around 6, vitreous luster, and color variability from pale yellow to green. These characteristics are illustrative rather than observational.

Discovery and naming: Kernellit has appeared in textbooks and theoretical papers as a didactic example rather than a confirmed natural mineral. To date, no verified mineral specimen or field occurrence has been documented in peer-reviewed publications, and the name is used to illustrate substitutions within KAlSi3O8-like frameworks.

Occurrence and formation: Because kernellit is hypothetical, its natural occurrence is speculative. If it existed, it would be expected in potassium-rich, silica-undersaturated metamorphic rocks or pegmatites, where framework silicates can tolerate significant cation substitution.

Significance: The concept of kernellit helps students understand solid-solution relationships in feldspars, crystal-chemistry constraints on framework structures, and the distinction between conjectural minerals and validated specimens. It serves as a teaching aid to discuss how substitutions influence physical properties and crystallography in silicate minerals.