This paper presents the archaeological contexts and results of analyses of slags, surface residues, and earthen-ware refractories from the third-millennium B.C. site of Göltepe in south-central Turkey. These materials are only part of a workshop/habitation assemblage at the site, which also includes ore nodules, multifaceted molds, and metal fragments as well as groundstone tools utilized in ore dressing and beneficiation. Twenty-four ceramic fragments of bowl-shaped crucibles were analyzed as a representative sample from some 250 examples excavated in the 1990 season. Analysis suggests the intentional production of tin metal by reduction firing of tin oxide (cassiterite, SnO₂) in crucibles. Tin oxide was identified on the interior surfaces of the crucible fragments by x-ray fluorescence, x-ray diffraction, scanning electron microscopy coupled with energy dispersive x-ray analysis, and wavelength dispersive microprobe analysis. The results of these tests have a direct bearing on the question of tin sources in ancient Anatolia.