The proton-induced x-ray emission (PIXE) technique has been applied to the analysis ofelement concentrations in obsidian samples for the classification of archaeological artifacts. No target preparation other than washing and the selection of a flat surface was undertaken. Thick target yields have been calculated and element concentrations derived from the detected x-ray spectra; concentrations are given for K, Ca, Ti, V, Mn, Fe, Ga, As, Rb, Sr, Y, Zr, Nb, Ta, and Pb. A pinhole filter is described which enables a single measurement of approximately 5-minute duration to give element concentration data over an x-ray energy range of 3-20 keV. -- AATA