Twelve Chozo Artifacts are needed to open the final path in Metroid Prime. Samus must recover the complete set before the Artifact Temple can unlock access to the Phazon Impact Crater on Tallon IV.
The artifacts are scattered across Tallon IV and its major regions, including the Chozo Ruins, Magmoor Caverns, Phendrana Drifts, and the Phazon Mines. Some are found through exploration, while others require defeating bosses or returning to previously visited areas with newly acquired abilities.
A common mix-up is confusing the twelve artifacts with other collectible sets in the game, such as Missile Expansions, Energy Tanks, or the Chozo Lore scans. The artifacts are a specific story-critical collection, and missing even one prevents Samus from entering the crater for the final confrontation.
The Artifact Temple stands above the crater created by the Phazon meteor. The Chozo built it as a containment structure, making the artifact hunt part of Tallon IV’s larger story rather than merely an optional scavenger hunt.