Structural chemistry of silicates: new discoveries and ideas

The new tetrahedral complexes revealed in the structures of natural silicates in the last years are analyzed. Several new minerals and structural types widen the structural classification and principles of silicates. The new structures of silicates with mixed anions are formed by stacking of similar units, and thus they can be described in terms of the modular approach and its polysomatic concepts. The difference between the silicate minerals of the Earth’s crust and mantle is considered. Possible mineral transformations occurring in the mantles of the Earth and extrasolar planets are described.