Uncorrupted Ore is an achievement that requires the player to smelt 100 corrupted ore in the Trahaearn Clan furnace, and then claiming the Smithing XP lamp from Lady Trahaearn.
Although this achievement is listed as having a level 89 Mining requirement, this is not actually needed for completion, as the player can receive corrupted ore from other sources than Seren Stones, such as from the Crystal chest.