Source : Webster's Revised Unabridged Dictionary (1913)

Geochemistry \Ge`o*chem"is*try\, n. [Gr. ?, ?, the earth +
   chemistry.]
   The study of the chemical composition of, and of actual or
   possible chemical changes in, the crust of the earth. --
   {Ge`o*chem"ic*al}, a. -- {Ge`o*chem"ist}, n.