Crocidolite

Cro‐cid″o‐lite (kr?–s?d″?–l?t), n. [Gr. κροκύσ nap on cloth + -lite.] (Min.) A mineral occuring in silky fibers of a lavender blue color. It is related to hornblende and is essentially a silicate of iron and soda; — called also blue asbestus. A silicified form, in which the fibers penetrating quartz are changed to oxide of iron, is the yellow brown tiger-eye of the jewelers.