How many elements have a rhombohedral crystal structure?

There are around 12 elements that naturally crystallize in a rhombohedral structure at room temperature. Some notable examples include carbon in the form of graphite, and certain allotropes of sulfur and boron. The rhombohedral structure is characterized by a unit cell that is a rhombohedron, where the angles are equal but not 90 degrees. This type of crystal system is less common compared to cubic or hexagonal structures.