Here's why:

* Abundance of Silicon and Oxygen: Silicon and oxygen are the two most abundant elements in the Earth's crust.

* Strong Bonding: Silicon and oxygen readily form strong, stable bonds, creating a wide variety of silicate structures.

* Diverse Structures: Silicate minerals exhibit a wide range of structures, leading to a diverse array of properties and appearances. This allows them to form a vast variety of rocks.

While silicates dominate, other mineral groups like carbonates, oxides, sulfides, and sulfates also play important roles in rock formation, but in lesser quantities compared to silicates.