This article does a good job of explaining why we use the metals we do as currency. Essentially, it boils down to the unique traits that are necessary for money being found in only a select few metals, namely gold and silver.
Think about what properties we would need for an element to be used as currency and take a look at the periodic table.
It would have to be solid at room temperature, so that rules out all the gases, as well as Mercury and Bromine which exist as liquid at that temp, as well as being toxic. Toxicity also means things like arsenic and the like are unsuitable.
It has to be stable, since nobody wants their money to combust or rust away to nothing, which rules out a fair portion of the remaining table. This also rules out metals like iron
It has to be easy to mine, smelt, and forge, even for a stone-age culture.
It has to be rare. If anyone can just go out, dig a hole, and find some money, it would have no value.
It can't be so rare that it is almost impossible to find, because there has to be enough to mint into currency or forge into jewelry/valuables