This text brings together a wide range of ideas and methods from geochemical literature, with the principle emphasis being on "whole-rock" chemistry. This text has two main goals - to put into the hands of a non-expert, who needs to make use of geochemical data, a summary of the methods and techniques currently used in geochemistry; and to collect the disparate techniques and methodologies used by geochemists into one volume. This text can be read at two levels - by a geochemist with data who wishes to evaluate and interpret that data, and by a geologist or geochemist who wants to understand some of the current geochemical jargon and make sense of geochemical literature. This text focuses particularly on examples chosen from the Archaean, and on igneous and metamorphic petrology.