What is the name of the copper mountain where the Sampo is buried?

The copper mountain where the Sampo is buried is called Vaskivuori.

In the Kalevala’s Sampo cycle, Louhi takes possession of the magical object after Ilmarinen forges it for Pohjola. She hides it deep inside a copper mountain, where it produces prosperity and abundance for the northern people. The Finnish name Vaskivuori literally combines vask(i), “copper,” with vuori, “mountain.”

The Sampo is often described as a miraculous mill or wealth-producing device, though the epic never gives it one completely consistent physical interpretation. It may produce flour, salt, and money, and its decorated lid has also been read symbolically as an image of the rotating sky or cosmic order.

The heroes of Kalevala later sail to Pohjola to recover the Sampo. Louhi resists them, transforming into a huge eagle during the battle. The struggle causes the Sampo to fall into the sea and shatter, scattering its fragments and ending its concentrated source of wealth. Pohjola mountain and Tuonela hill are not the standard names for its hiding place.