Agate is not a single element, so it doesn't have an atomic number.

Agate is a variety of chalcedony, which is a microcrystalline form of silica. Silica is primarily composed of silicon dioxide (SiO2).

Here's the breakdown:

* Silicon (Si) has an atomic number of 14.

* Oxygen (O) has an atomic number of 8.

Agate's composition is primarily silicon dioxide, but it can also contain small amounts of other elements like iron, manganese, and aluminum, which give it its variety of colors.