The Collaborative International Dictionary of English v.0.48:

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. It varies in color from white
   to dark green. It is the more common and less valuable
   variety of jade, the other being jadeite. Large deposits are
   found in Australia. Called also nephritic stone. See also
   Jade. --[MW10]
   [1913 Webster +PJC] Nephritic

WordNet (r) 3.0 (2006):

nephrite
    n 1: 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