https://www.sciencedaily.com/releases/2019/04/190411131540.htm

Unlike its carbon cousin, two-dimensional borophene can't be reduced from a larger natural form. Bulk boron is usually only found in combination with other elements, and is certainly not layered, so borophene has to be made from the atoms up. Even then, the borophene you get may not be what you need.

For that reason, researchers at Rice and Northwestern universities have developed a method to view 2D borophene crystals, which can have many lattice configurations -- called polymorphs -- that in turn determine their characteristics.