20 fragments of crucibles from the Pfyn culture from five Swiss proveniences were investigated by optical microscopy, XRD, XRF and electron microscopy. The crucibles are made of local, lightly tempered, high-CaO and low-CaO clays, and most of them were tempered with threshing waste (chaff). The uppermost parts of the crucibles are swollen, respectively melted, which may be explained by the use of blow-pipes acting upon the crucibles from above. The inner areas of the crucibles show a significantly higher concentration of copper than do the parts which face away from the blow-pipes. In the scoeified areas mostly chalcopyrite and less frequently copper, cuprite, bornite and chalcanthite are to be found. If use as casting crucibles seems the most plausible, certain crucibles may perhaps also have been used for smelting sulphide ores.