Eridium is a currency in Borderlands 2
Used to purchase upgrades at Crazy Earl’s Black Market in Sanctuary.
Background[edit]
Eridium is a new currency in the game. It's the most valuable currency, much more rare than the money.
You use Eridium to buy your capacity upgrades. So if you want to get your backpack larger, or carry more ammunition, you really want to hoard and collect your Eridium so you can buy those upgrades.
