Mudelite

Mudelite is a fictional mineral used in educational contexts to illustrate clay-mineral concepts in mud-rich rocks. It is described as a hydrated aluminosilicate with a layered, sheet-like structure and variable composition, commonly imagined to include aluminum and silicon with iron or magnesium substituents. Because mudelite is not a recognized mineral species, its exact chemical formula is not fixed in authoritative references.

Occurrence and formation: In illustrative descriptions, mudelite forms during diagenesis of fine-grained sediments under low-temperature, low-pressure conditions, and is typically found in mudstones and siltstones. It is often depicted as coexisting with real clay minerals such as illite and smectite and can arise from alteration of feldspars or feldspar-rich rocks.

Properties: As a model clay mineral, mudelite is described as a soft material with Mohs hardness around 2–3, a dull to pearly luster, and a color range from light brown to olive-green. It is usually micrometric or nanoscale in particle size and lacks long-range crystallinity, appearing amorphous or microcrystalline under standard petrographic examination. It may show basal texture in thin section and a tendency to form platy aggregates typical of phyllosilicates.

Classification and notes: Mudelite sits within the broader category of phyllosilicates in teaching models but is not listed as a distinct mineral species by major mineral databases or the IMA. It is primarily used as a didactic placeholder to discuss diagenetic clay formation and textural relationships in mudstones.

See also: clay minerals, illite, smectite, diagenesis, phyllosilicates.