Quartz is made of silicon dioxide (SiO2). It's a very common mineral found all over the world.

Here's a bit more detail:

* Silicon (Si) is the main component of quartz. It's a metalloid, meaning it has properties of both metals and nonmetals.

* Oxygen (O) is the other element present in quartz. It's a highly reactive nonmetal.

These two elements combine in a specific arrangement to form the crystalline structure of quartz. This structure is what gives quartz its unique properties, including hardness, resistance to scratching, and its ability to refract light.