E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
or Aettes (ε). Yellow clay ironstones supposed to have sanative and magical virtues. They are so called because they are found in eagles nests. Epiphanius says, In the interior of Scythia there is a valley inaccessible to man, down which slaughtered lambs are thrown. The small stones at the bottom of the valley adhere to these pieces of flesh, and eagles, when they carry away the flesh to their nests, carry the stones with it. The story of Sindbad in the Valley of Diamonds will occur to the readers of this article (Epiphanius: De duodecim gemmis, etc., p. 30; 1743).
It is said that without these stones eagles cannot hatch their eggs.