Source : Webster's Revised Unabridged Dictionary (1913)

Actinolite \Ac*tin"o*lite\, n. [Gr. ?, ?, ray + -lite.] (Min.)
   A bright green variety of amphibole occurring usually in
   fibrous or columnar masses.

Source : WordNet®

actinolite
     n : a green mineral of the amphibole group; calcium magnesium
         iron silicate