Gold

Gold is a metal that has no use yet, but will in the future.

Rarity
Gold is extremely common. Some countries produce tens of thousands of tons of it per year.

Uses
There is no use for gold yet, except for giving it to the olympics winner as a prize. Possibly, it could be used to make bullets in the case of lead/copper shortage.

Future Uses
If and when the CCRP 2 reaches the point of computers (1940), gold will be used for computer chips, which will be required to make them.