Aquamarine is not a sedimentary rock. It is a gemstone, which means it's a mineral.

Here's why:

* Sedimentary rocks are formed from the accumulation and cementation of sediments, like sand, mud, or shells.

* Minerals, like aquamarine, are naturally occurring inorganic solids with a specific chemical composition and crystal structure. Aquamarine is a variety of the mineral beryl.

Aquamarine forms deep within the Earth's crust through geological processes involving heat, pressure, and chemical reactions.