Page "Mineral" Paragraph 63

Orthosilicates consist of isolated tetrahedra that are charge-balanced by other cations.

Also termed nesosilicates, this type of silicate has a silicon: oxygen ratio of 1: 4 ( e. g. SiO < sub > 4 </ sub >).

Typical orthosilicates tend to form blocky equant crystals, and are fairly hard.

Several rock-forming minerals are part of this subclass, such as the aluminosilicates, the olivine group, and the garnet group.