In mythology, what was Medusa's hair made from?

In Greek mythology, Medusa, also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those who gazed into her eyes would turn to stone.

Medusa was beheaded by the Greek hero Perseus, who then used her head, which retained its ability to turn onlookers to stone, as a weapon until he gave it to the goddess Athena to place on her shield. In classical antiquity, the image of the head of Medusa appeared in the evil-averting device known as the Gorgoneion.

The three Gorgon sisters—Medusa, Stheno, and Euryale—were all children of the ancient marine deities Phorcys (or "Phorkys") and his sister Ceto (or "Keto"), chthonic monsters from an archaic world.

While ancient Greek vase-painters and relief carvers imagined Medusa and her sisters as having monstrous form, sculptors and vase-painters of the fifth century BC began to envisage her as being beautiful as well as terrifying.

In a late version of the Medusa myth, by the Roman poet Ovid, Medusa was originally a beautiful maiden, but when Neptune/Poseidon had sex with her in Minerva/Athena's temple, Minerva punished Medusa by transforming her beautiful hair into horrible snakes.