Cyclosilicate

The cyclosilicates are mineral of the family of the Silicate S. the structural unit of the cyclosilicates consists of formed cycles of tetrahedrons connected to each other by pooling of an oxygen and a report/ratio If: O = 1: 3. These cycles are generally piled up in the structure and determine channels which can be empty or occupied by ions or molecules. The cyclosilicates are classified on the basis of type of rings: to three 6-, four 8- and six tetrahedrons 12-.

The cyclosilicates with a ring include in particular:

  • the Tourmaline S, which is a group of borosilicates out of rings with six tetrahedrons and many isomorphic replacements ;
  • the Beryl and the Cordierite, out of rings with six tetrahedrons, which are touts occupied by silicon in beryl, while in cordierite 5 silicon atoms and 1 aluminum atom are distributed in the six tetrahedrons. Cordierite is formed easily if the temperature increases in the sediments more or less rich in Mg, with 800°C and 1000 bars of water pressure. As for the form without Mg of the whole, it is a phase which exists in the ternary diagram SiO2 - Al2O3 - FeO and it was announced in the blast furnaces.
  • the Dioptase CuSiO2 (OH) 2
  • of others made up belong to this family of silicates: Bénitoïte BaTiSi3O9, Axinite Ca2Fe2+Al2BO3Si4O12 (OH), Papagoïte CaCuAlSi2O6 (OH) 3.

The cyclosilicates with condensed rings include in particular:

  • the Milarite of formula: K2Ca4Al2Be4Si24O60.H2O
  • the Osumilite often confused with the cordierite but which belongs to the volcanic rocks and has a spectrum X-ray different from this one.

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