In Greek mythology, Pandora’s vessel was made of clay according to Hesiod’s earliest surviving account.
Hesiod’s Works and Days describes Pandora receiving a large storage jar. The Greek word is pithos, a substantial earthenware container used in the ancient Mediterranean for storing goods such as grain, oil, or wine. The vessel is therefore an everyday ceramic object, not a jeweled chest.
The familiar phrase “Pandora’s box” developed later through translation history and artistic tradition. The Latin writer Erasmus used the word pyxis, meaning a small box or container, when translating the story. That choice helped establish the box image in European languages.
Ancient pottery could be decorated and valuable, but Hesiod does not make the vessel a golden or magical treasure chest. The important feature is what it contains and the act of opening it. “Clay” is the standard concise answer for the material associated with the earliest surviving version.