From Metroid Wiki
Denzium is a durable material found in Metroid Prime 2: Echoes that can only be destroyed by Samus's Power Bomb upgrade. It was fashioned by Luminoth Mechanoids, who had turned against their creators, to block access to key areas.
- "The machines have fashioned a new alloy of considerable strength. They use this metal to block access to key areas. Destroy it if you can!" —O-Lir (Metroid Prime 2: Echoes)
- "Block contains Denzium. The local creatures have weakened it, along with time and erosion." —Scan Data (Metroid Prime 2: Echoes)