What does fibrous mean in mineralogy ?

Fibrous : definition

Fibrous is an adjective which designates a crystal or an aggregate of elongated crystals in the form of fibers (boulangerite, sepiolite, etc.), which can evolve into a habit or an acicular texture by elongation of the crystals. A fibrous break refers to an irregular break surface with coarse fiber flow, usually obtained by breaking fibrous crystals.