Example of a three-dimensional silicate is :

Solution :
The feldspars are most abundant aluminosilicate minerals in the Earth surface. The silicon atoms and aluminium atoms occupy the centres of interlinked tetrahedra of $$SiO_4^{4 - }$$  and $$AlO_4^{5 - }.$$  These tetrahedra connect at each corner to other tetrahedra forming an intricate, three dimesional, negatively charged framework. The sodium cations sit within the voids in this structure.