Silica sand is primarily composed of quartz, which is a mineral. While technically not a rock type itself, it's considered a sedimentary rock fragment.

Here's why:

* Quartz is a very hard and resistant mineral, making it durable enough to withstand weathering and erosion.

* Silica sand is formed when larger quartz-containing rocks break down into smaller grains.

* Sedimentary rocks are formed from the accumulation and cementation of these fragments.

So, while silica sand is made up of quartz, it's considered a sedimentary rock fragment rather than a specific rock type on its own.