Fe2Mg3Al2Si4O12OH2

Fe2Mg3Al2Si4O12OH2 is a chemical formula that describes a hydroxyl-bearing silicate with a composition and structural features reminiscent of talc-like minerals. The arrangement implies a layered silicate framework in which silicon tetrahedra form sheets and iron, magnesium, and aluminum occupy octahedral sites within a connected sheet, with hydroxyl groups present in the structure. In practice, such a composition represents a mixed-cation end-member within a phyllosilicate system that resembles the talc group (which is typically Mg3Si4O10(OH)2), but with substitutions that introduce iron and aluminum.

Classification and structure

If realized in nature, this formula would place the mineral in the phyllosilicate family, characterized by parallel sheets of silicate tetrahedra linked to octahedral sheets and separated by weak van der Waals or hydrogen-bonded interlayers. Substitution of Mg2+ by Fe2+ and incorporation of Al3+ into octahedral sites would influence layer charge, spacing, and physical properties. The presence of two hydroxyl groups (OH) is consistent with other hydroxyl-bearing sheet silicates, contributing to hydrogen bonding and potential interlayer interactions.

Occurrence and significance

As of the current mineral databases, there is no widely recognized mineral with the exact formula Fe2Mg3Al2Si4O12OH2. It is best described as a hypothetical or synthetic end-member used to explore solid-solution behavior in talc-like phyllosilicates and to model how Fe, Mg, and Al substitutions might balance charge and affect structure. Such a composition is of interest in crystallography and mineral chemistry for understanding substitution mechanisms in layered silicates.

Properties and synthesis

If synthesized or discovered, the mineral would likely display characteristics typical of talc-like phyllosilicates: very low hardness, pearly to dull luster, and a tendency toward perfect basal cleavage. Color would be influenced by iron oxidation state, potentially ranging from pale to greenish-brown. Experimental synthesis could be pursued under hydrothermal or high-temperature, low-pressure conditions to stabilize the layered structure with mixed Fe, Mg, and Al.