Proton induced x-ray emission analysis has been used for the determina-tion of minor and trace element concentrations in obsidian artifacts. Thin targets were made from the acid digests of 30-100 mg of finely powdered obsidian samples. Concentrations are reported for K, Ca, Ti, Ba, Mn, Fe, Zn, Ga, Cu, Pb, Br, Rb, Sr, and Ar in 49 obsidian artifacts from Northern Campeche, Mexico. Methods used for the association of obsidian artifacts with geological sources are illustrated. -- AATA