An important attribute of obsidian for archaeological investigation is that obsidian flows are chemically distinctive allowing artifacts to be chemically linked to their geological source areas. These chemical differences in obsidian are the result of certain elements crystallizing to solids and being removed from the magma as per the Bowen reaction series, resulting in a distinctive geochemistry for lava from most magma chambers and sometimes for each extruded lava flow. Prior to, and during, a volcanic eruption, magma evolves as changes in temperature and pressure causes chemical differentiation and leads certain minerals to crystallize and settle out of the melt.

As magma evolves, further melting and crystallization change the nature of the solids, and crystals that accept the incompatible elements may form in the liquid. Some feldspars, for instance, are good hosts for strontium, as is mica for rubidium. "Evolved" obsidian magmas may contain these crystal "hosts," and the ratio of a given element between the liquid and solid phases will change dramatically. Changes of this kind issue a particular chemical character to a given obsidian…The result of these processes is that the incompatible-element mix of a given obsidian source varies from any other and becomes a sensitive indicator of origin (Shackley 2005: 10-11).

This process creates detectable chemical differences in obsidian that permits methods such as X-ray florescence (XRF), Instrumental Neutron Activation analysis (INAA), and various types of inductively coupled plasma mass spectrometry (ICP-MS), and Proton-induced X-ray emission-proton-induced gamma ray emission (PIXE-PIGME) to chemically characterize the material (Neff and Glascock 1995;Shackley 1998).