pot metal

Short definition from Wiktionary

Noun

1. 1
   The metal from which iron pots are made, different from common pig iron.
2. 2
   An alloy of copper with lead used for making large vessels for various purposes in the arts.
3. 3
   A kind of stained glass, the colours of which are incorporated with the melted glass in the pot
4. 4
   Synonym of monkey metal.