Yes. Use ingots to boost your chances of receiving rare items from the islands. Simply add one when preparing a ship: the more valuable the ingot you use, the better your chances are of receiving more goods.
Ingots also give you a better shot at treasure chests with rewards inside. The more valuable the ingot you use, the better your chances are of receiving a treasure chest (ships without ingots don't come back with treasure chests).
Finally, don't forget that you can temporarily improve ingot effectiveness when dispatching ships by activating the Favorable Voyage booster at the Lab.
You can up your chances of getting rare goods by upgrading the islands at the Academy of Industry as well.