hawk's-eye

hawk's-eye

n
(Minerals) a dark blue variety of the mineral crocidolite: a semiprecious gemstone
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
While studying the chemistry of hawk's-eye, a blue form of tiger's-eye, he found that the gem was almost entirely quartz but that it also contained fibers of crocidolite, an often bluish, iron-bearing form of asbestos.