I'm getting started with solid state physics and I've already seem sometimes people taking about the crystal structure of an element.
So for instance: polonium is said to have a cubic crystal structure, while carbon is said to have a simple hexagonal crystal structure.
But wait a minute, when we talk about structures like this, aren't we talking about macroscopic solids?
The understanding I have is: we have a macroscopic solid, it is made out of atoms, and we are able to say the structure the atoms are organized.
But carbon, polonium and so forth are just elements. They are atoms, they are not macroscopic solids. So what does it mean to talk about the crystal structure of an element?