Source : Webster's Revised Unabridged Dictionary (1913)

Nephrite \Neph"rite\ (?; 277), n. [Cf. F. n['e]phrite. See
   {Nephritis}.] (Min.)
   A hard compact mineral, of a dark green color, formerly worn
   as a remedy for diseases of the kidneys, whence its name;
   kidney stone; a kind of jade. See {Jade}.

Source : WordNet®

nephrite
     n : an amphibole mineral consisting of calcium magnesium
         silicate in monoclinic crystalline form; a source of jade
         that is less valuable than from jadeite; once believed to
         cure kidney disorders