Here's why:

* No Cleavage: Quartz has a conchoidal fracture, meaning it breaks in smooth, curved surfaces. This is why it doesn't show cleavage planes.

* Hardness of 7: Quartz is a relatively hard mineral, ranking 7 on the Mohs Hardness Scale. It can scratch glass.

* Composition SiO2: Quartz is composed of silicon dioxide (SiO2).

Let me know if you have any other mineral riddles!