Fe2Mg2Al9Si4O22OH2

Fe2Mg2Al9Si4O22OH2 is the chemical formula for a complex iron–magnesium aluminosilicate hydroxide. The composition indicates a highly aluminous silicate with a tetrahedral framework built from silicon and aluminum and with iron and magnesium occupying octahedral sites, together with hydroxyl groups integrated into the structure. In mineral-chemical terms, such a formula suggests a layered or sheet silicate (a phyllosilicate-type structure) where aluminum can substitute for silicon in tetrahedral positions and Fe and Mg populate octahedral layers.

Classification and naming in minerals: as of now, there is no widely recognized mineral species that is officially described with this exact formula. It may represent an end-member composition within a broader aluminosilicate or chlorite/mica-related subgroup, or serve as a theoretical or synthetic reference composition. In practice, minerals with similar features are typically grouped among phyllosilicates or clay/mica-like minerals, where alumina-rich sheets and Fe/Mg-bearing octahedra are common.

Occurrence and formation: if a natural phase corresponding to this composition exists, it would be expected to form under metamorphic or hydrothermal conditions that promote the crystallization of aluminum-rich silicate sheets with iron and magnesium in octahedral layers. The exact crystal structure, orientation, and physical properties would depend on the specific mineral group and the degree of substitution within the layers.

Properties: specific optical, thermal, and mechanical properties are not defined for this exact formula and would depend on the resulting mineral species it represents, were such a mineral to be formally described.

See also: aluminosilicate minerals, phyllosilicates, chlorite group, mica group.