geomembraanit

Geomembraanit is a proposed mineral in the silicate family, defined by a layered, sheet-like structure and a composition that can accommodate a range of alkali and earth-alkaline cations. The name combines geo—earth—with membran—membrane—reflecting its laminar, flexible sheets.

Crystallography and composition: It is described as a hydrated phyllosilicate with alternating silicate sheets and interlayer water or hydroxyl groups. The framework allows substantial substitution among Mg, Fe, Al, and Na, leading to a solid solution series. The mineral is typically microcrystalline, with sheet-like morphology and a tendency to form pliable, transparent to translucent masses.

Physical properties: Geomembraanit is soft and flexible, with a Mohs hardness of about 3–4, a pearly to vitreous luster, and a white to pale green or gray color, depending on composition. It shows cleavage along basal planes and can absorb moisture, causing slight expansion.

Occurrence and formation: It is reported to form in hydrothermal systems where basaltic fluids interact with aluminous rocks, and in metamorphosed carbonate formations under low-grade conditions. It is rare and has mostly been identified in experimental syntheses; natural samples remain scarce and under debate among researchers.

Etymology and status: The name derives from geological nomenclature and the mineral's membrane-like sheets. As described here, geomembraanit is a hypothetical mineral not yet recognized in major mineralogical catalogs, and its definition is subject to revision pending peer-reviewed confirmation.