bolsterit

Bolsterit is a hypothetical mineral used in materials science and mineralogy education as a model reinforcing phase in composites. It is not recognized as a real mineral by major authorities such as the International Mineralogical Association. The name refers to its proposed role in improving structural performance under stress.

Bolsterit is conceptually a layered silicate with a 2:1 structure, comprising octahedral sheets of magnesium and aluminum linked to tetrahedral silica layers. An idealized formula is (Mg,Al)2Si4O10(OH)2. In this model, the layers form strong in-plane bonds with weaker interlayer interactions, allowing controlled delamination and toughness.

In models, bolsterit has a Mohs hardness of about 5–6, a measured density around 2.9 g/cm3, and a vitreous to pearly luster. Crystallization is assumed to be monoclinic, with good basal cleavage along the (001) plane. Color ranges from pale gray to steel blue in simulated crystals.

Bolsterit does not occur in nature. It is typically synthesized in laboratories by hydrothermal or solid-state methods from magnesium- and aluminum-rich silicates in the presence of alkaline water. In simulations, it is treated as a stable reinforcement phase with tunable layer spacing.

Uses include educational demonstrations of layered silicate reinforcement, computer modeling of fracture mechanics in composites, and as a placeholder mineral in textbooks. The term bolsterit is widely used in thought experiments but is not part of established mineral data. See also phyllosilicate, silicate minerals, composite materials.