The Collaborative International Dictionary of English v.0.48:

Chlorite \Chlo"rite\, n. [Gr. ? (sc. ?), fr. chlwro`s light
   green.] (Min.)
   The name of a group of minerals, usually of a green color and
   micaceous to granular in structure. They are hydrous
   silicates of alumina, iron, and magnesia.
   [1913 Webster]

   Chlorite slate, a schistose or slaty rock consisting of
      alumina, iron, and magnesia.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Chlorite \Chlo"rite\, n. [Chlorous + -ite.] (Chem.)
   Any salt of chlorous acid; as, chlorite of sodium.
   [1913 Webster]

WordNet (r) 3.0 (2006):

chlorite
    n 1: a generally green or black mineral; it occurs as a
         constituent of many rocks typically in the form of a flat
         crystal