Fibrous

A gem is said to have a fibrous look if, as the  name suggests, it has a cloth-like appearance.  This  is  usually  created  by  the  gem  having  a  structure where the crystals or the inclusions are  parallel to each other.  Kyanite and Scapolite  are often said to have a fibrous lustre and many  gemstones that demonstrate chatoyancy also are fibrous.