A young child
    picked up a piece of gold that had been lost
Question

                We were at the sea-side and my son
      brought me something shiny that turned out to be a piece of gold. What should we do with
      it?
Praise be to Allah.If a young child or a person who is insane finds something 
  that has been lost, and picks it up, then his guardian should take on the responsibility 
  of identifying its owner in his place. The guardian should take it because they 
  are not qualified to be entrusted with it or to take care of it. If he leaves 
  it in their hands and it gets damaged, he will be held responsible because he 
  neglected it. If the guardian (of the child or insane person) announced it and 
  tried to identify the owner, and nobody comes forward to claim it, then it belongs 
  to the child or insane person, as is the case of the adult or sane person [who 
  finds lost property]. For more details on the rulings pertaining to lost property 
  see Question # 5049