Raman spectra and molecular structure of silicates

The frequencies of the strong Raman bands of silicates corresponding to the Si₂O ₅ ^2? complex anion and the SiO₂ molecule have been determined. This revealed the presence of these anions in silicates with double rings or double chains and various types of layers and the presence of SiO₂ molecules in silica modifications, feldspars, zeolites, and zircon group orthosilicates. A similarity between the Raman spectra of olivine group orthosilicates and garnet and phenacite group orthosilicates was found. This similarity was attributed to the existence of distorted tetrahedra in all of these groups, having disordered orientation in the garnet and phenacite groups.