It means just what it sounds like -- something is really hard.
iron and copper are hard materials .
Cast iron
Yes they can. Iron doors are very hard but not hard enough.....
its like really really hard
Tetsu or Kurogane is iron.
Yes.
Hard...
Iron
its not hard enough
No, iron pyrite, unlike iron, is not malleable at all. It is a hard, inflexible rock.
. Examples of hard magnets are Aluminum-Nickel-Cobalt (Alnicos) and Strontium-Iron (Ferrites, also known as Ceramics).
Ferrous means pertaining to iron.