Here's why:

* Durability: Quartz is incredibly hard and resistant to weathering and erosion. This makes it survive the breakdown of rocks and the constant battering of waves, allowing it to accumulate on beaches.

* Abundance: Quartz is one of the most common minerals in the Earth's crust, making it readily available to form beach sand.

While quartz dominates, other minerals like feldspar, mica, and even fragments of shells can also be found in beach sand, depending on the location and geological history of the area.