I noticed over at hack/ yesterday a nice article on the use of gold coinage in RPGs. This nicely complements an article I'd been kicking around on electrum, so I finally decided to finish it up.
Electrum is sort of the red-headed stepchild of fantasy gaming coinage--neither fish nor fowl, and often discarded altogether. Many folks know the basics--electrum is a naturally occurring alloy that sees silver mixed with gold (and a just a hint of a few lesser metals). One electrum piece was worth 5 silver pieces in pre-3e D&D. But let's take a look at why this odd duck may not be as odd as some folks think, and why there may be a place for it after all.
First, why such a "electrifying" name? Well, electrum (the metallic composite) shared its name in Greek with amber, which was noted for its electrical properties. We get the name "electrum" from the Latin translation for the Greek name for these items, and that's actually the base for our word "electricity".
Historically, electrum was used for coinage from cultures stemming from ancient Anatolia to the cities of Greece. As it is more durable than the softer pure element of gold, it was favored over gold in coinage (also in part because gold refining wasn't too advanced as of yet). One of the big issues this sort of coinage had, however, was the fact that the composition ratio of gold to silver would vary wildly (if you use electrum in your game, remember this--it can be great for use with a failed Appraise roll or being swindled by a merchant in unfamiliar lands). So there's definitely a historical basis for this denomination of coin.
Outside of coinage, electrum did have some other uses. It was used in diningware, such as cups and plates. It also decorated monuments and obelisks from ancient Egypt onward. Forget about seeing it in mundane weapons, although Hesiod mentions it as part of the Shield of Hercules (electrum is also mentioned in Homer, but with the translations, there's always the question of whether they actually mean metallic electrum or amber). Volo's Guide to the North for Forgotten Realms did have an electrum-plated magical morning star called the Storm Star with electrical attack properies. If you are going to include electrum in a magical weapon, something with an electrical lightning effect may be the way to go, as electrum is an excellent electrical conductor.
Pliny the Elder alleged that a cup made of electrum could discern whether or not the drink therein was poisoned, by reflecting a rainbow-esque pattern within, and by sparking and hissing. Not a bad idea for a magical item!
Aside from that, electrum in the occult also has been referenced as a tell-tale--a marker of veracity and truth. Perhaps an enchanted electrum pendant to give a bonus for Detect Lie or Gather Information?
Even if you don't want to fall back to an earlier coinage system for your fantasy RPG, you may consider throwing in a few electrum coins or items--perhaps the rare coins of some ancient civilization, or a goblet that a paranoid king seeks to ensure his wine is not poisoned. If you do end up using electrum, remember you're in good company.