Mudellites

Mudellites are a group of fine-grained aluminosilicate minerals within the broader phyllosilicate family. They were named after the Mudell Formation, the type locality where the minerals were first described. Mudellites are characterized by a layered sheet structure, variable hydration, and a tendency to form platy crystals in sedimentary rocks.

Chemically, mudellites comprise aluminum silicate with variable amounts of magnesium, iron, potassium, and water in interlayer spaces. They typically display a Mohs hardness of 2 to 3, a dull earthy luster, and a color range from white to pale yellow or greenish in well-formed grains. They exhibit perfect basal cleavage and a relatively high cation-exchange capacity for a clay mineral, enabling adsorption of nutrients and other cations from pore waters.

Geologically, mudellites form during diagenesis of clay-rich sediments under low-temperature, low-pressure conditions that promote authigenic clay alteration. They are commonly associated with mudstones and shales and may occur alongside other clay minerals such as illite and smectite. Reports of mudellites come from several sedimentary basins worldwide, spanning a range of climatic settings.

Research on mudellites focuses on their formation pathways, interlayer hydration dynamics, and potential uses as adsorbents or ceramic raw materials. They are not widely exploited industrially due to their rarity but are of interest in studies of diagenetic clay systems and sedimentary mineralogy.

See also: illite, smectite, clay minerals.