Silicates are minerals that contain silicon and oxygen, often combined with other elements like aluminum, magnesium, iron, calcium, sodium, and potassium. They make up about 90% of the Earth's crust.

Here's why silicates are so common:

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

* Versatile bonding: Silicon and oxygen can bond in a variety of ways, creating diverse structures and mineral types.

* Stability: Silicates are generally very stable under Earth's surface conditions.

Some common examples of silicate minerals include:

* Quartz: A pure silica mineral (SiO2)

* Feldspar: A group of minerals containing aluminum, silicon, and various other elements

* Mica: A group of minerals with layered structures

* Pyroxene: A group of minerals with single chains of silicate tetrahedra

* Amphibole: A group of minerals with double chains of silicate tetrahedra

So, when you think about the Earth's crust, you're primarily thinking about silicates!