Liberation refers to freeing valuable minerals from the host rock (i.e., gangue). To liberate the minerals, the ore must be ground to a particle size near that of the valuable mineral particle size.

In the case of diamonds, once they are liberated from the gangue, they can be concentrated and sold. In the case of metal ores, once the metal-bearing minerals are liberated from the gangue, they must be concentrated and then converted into actual metals prior to sale.

Figure: valuable minerals must be liberated from gangue minerals in order to produce a concentrate for further refining or a salable produce.