Guide
What Is Eridium Used for in Borderlands 4?
Eridium is the premium currency on Kairos used for Maurice black market purchases, select vendor unlocks, and late-game upgrade sinks — not a substitute for Golden Keys.
Earn Eridium from bosses, Order bunkers, vault clears, and some story/DLC chests.
Spend it first on Maurice's weekly featured legendaries that match your Vault Hunter build.
Secondary sinks include vendor inventory refreshes and cosmetic or upgrade stations that appear after mid-campaign.
Do not confuse Eridium with Golden Keys: keys open safehouse golden chests; Eridium pays for black market and upgrade loops.
If you are short on Eridium before a weekly reset, run Bio-Bulkhead and Dominion chest routes — both drop reliable piles.
Last verified Oct 20, 2026
FAQ
What is Eridium used for in Borderlands 4?
Maurice black market purchases, select vendor unlocks, and late-game upgrade sinks. It does not open golden chests.
How do I get Eridium fast?
Boss farms (Bio-Bulkhead, Bloomreaper), Order bunker clears, and high-tier Vaults after you have Vault Key Fragments.