Describes an absolute and nondestructive analytical technique that can be used, in combination with x-ray fluorescence, for the quantitative characterization of archaeological metal alloys. The method is based on the measurement of the average gamma ray absorption coefficient of the sample that is, for homogeneous materials, a linear function of the component concentrations. The average gamma ray absorption coefficient of different types of ancient metal objects was measured by means of a ¹³³Ba source; the concentration of the alloy components was then derived by solving the resulting system of equations by means of a weighted least squares technique.