Corundum (structure)

Corundum is a crystalline form of aluminum oxide (Al₂O₃) and is known for its hardness and durability. It has a hexagonal crystal structure, specifically belonging to the trigonal crystal system. The unit cell of corundum is characterized by a structure in which aluminum ions are surrounded by oxygen ions, creating a strong ionic bond. In terms of its lattice parameters, corundum typically has a hexagonal arrangement with space group R-3c (or D3d).