"Cyclosilicates": ring silicates - SiO₃

3, 4 or 6 tetrahedra linked - each tetrahedron shares a total of 2 oxygens with two different neighboring tetrahedra, building ring structures

6-member rings are the most common

3-member ring - Si3O9

4-member ring - Si4O12

6-member ring - Si6O18 e.g., beryl, tourmaline

Si:O ratio is 1 : 3

Examples of Cyclosilicates:

Beryl Be₃Al₂Si₆O₁₈

Tourmaline (Na,Ca)(Li,Mg,Al)(Al,Fe,Mn)₆(BO₃)₃(Si₆O₁₈)(OH)₄

 

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