(1) Minerals : The elements or com - pounds, which occur naturally in the earth's crust are known as minerals.
(2) Ores : The minerals which contain a very high percentage of a particular metal and it can be extracted profitably from them are called ores.
(3) Gangue : Ores obtained from the earth's crust does not contain ores of elements only, but ores are usually contaminated with large amount of impurities such as soil, sand, compounds of other metals, etc., which are called gangue.
OR
The impurities present in ore are called gangue.