'Earthen' in the Bible

Thus said Yahweh, Go, and buy a potter's earthen bottle, and [take] of the elders of the people, and of the elders of the priests;

Thus says Yahweh of Armies, the God of Israel: Take these deeds, this deed of the purchase which is sealed, and this deed which is open, and put them in an earthen vessel; that they may continue many days.