Herrendgrund partially gilt double drinking cut in the shape of a barrell
Because of the peculiar geological properties of the region, the local water had a high concentration of copper sulphate. Iron scraps were placed in hollows where the water collected and reacted with the copper sulphate to precipitate copper out of solution. The copper either settled as a sludge or formed a crust over the surface of the iron. This gave rise to the legend that the water had mysterious, if not magical, properties. Such cups are often engraved with rhymes or adorned with small models of miners at work. These puzzle cups were popular throughout Europe from around 1500 to the middle of the 18th century, after which time popular knowledge of chemistry increased and this type of object inevitably became less attractive.
Nothern Hungary ca 1740