Classification of Ores
There are combined state ores are generally found in the form of oxides, sulphides, carbonates, sulphates, chlorides and silicates.

Sources from earth, living systems and in sea sources from earth
Estimated 80 elements are obtained from mineral deposits on or beneath the surface of the earth.

Purification of Ores
The purification of ore means removal of gangue from the powdered ore. This process is otherwise called concentration of the ore or ore dressing. The purification or concentration of ore can be brought about in the following ways, depending upon the type of ore.
– Gravity separation process or hydraulic washing
– Froth flotation process
– Electromagnetic separation process
– Chemical method