A variant of tiger's eye, with a grey to grey-green lustre. The colour arises from differing degrees of oxidation as crocidolite is replaced by silica.

Tiger's eye (gold), hawk's eye (blue-grey), eagle eye (grey)—all variants of the same mineral, separated only by the extent of oxidation. Eagle eye is the most advanced stage. The same stone, at its oldest.

Primarily found in South Africa and Australia. Far less commonly traded than tiger's eye. A stone you meet only if you go looking.