(I) Although iron is the most common metal, it was the
last to be used by people. (II) Humanity made a huge
advance when people learned how to use metals.
(III) Metal tools were easier to shape than stone ones,
and could be mass-produced using molds. (IV) Unlike a
stone axe, which was useless when broken, a copper or
bronze one could be melted down and recycled.
(V) Shiny metals, such as gold and silver, were also
perfect materials for jewellery and coins