(ˌmɛtəˈsəʊməˌtɪzəm) or metasomatosis (ˌmɛtəˌsəʊməˈtəʊsɪs)
noun
change in the composition of a rock or mineral by the addition or replacement of chemicals
Word origin
C19: from New Latin; see meta-, somato-
metasomatism in American English
(ˌmɛtəˈsoʊməˌtɪzəm)
noun
the metamorphic process by which minerals of a rock or ore body are replaced by minerals of a different chemical composition as a result of the action of a fluid, esp. of moving water