Ēa'gle-stōne, n.

n. (Min.) A variety of argillaceous oxide of iron, occurring in rounded or ovoidal masses, varying from the size of a walnut to that of a man's head, having usually a concentric structure, often hollow within, with a loose kernel at center. They are natural concretions, and were so called by the ancients, who held the opinion that the eagle transported them to her nest to facilitate the laying of her eggs. Dana.