Extracting Metals Low in the Activity Series
Metals low in the activity series are very unreactive. The oxides of these metals can be reduced to metals by heating alone. For example, cinnabar (HgS) is an ore of mercury. When it is heated in air, it is first converted into mercuric oxide (HgO). Mercuric oxide is then reduced to mercury on further heating.
Similarly, copper which is found as Cu2S in nature can be obtained from its ore by just heating in air.