1. Gangue:
The impurities associated with the minerals are known as Gangue or Matrix.
2. Slag:
A compound formed when gangue is combined with flux is called slag.
Flux + Gangue → Slag
For example, the oxide of iron can be reduced by carbon monoxide as follows:
Fe2O3 + 3CO → 2Fe + 3CO2
In this extraction a basic flux, limestone is used. Since the silica gangue present in the ore is acidic in nature, the limestone combines with it to form Calcium silicate (Slag).
