Steelyard counterweight in the shape of the bust of an empress. The shell is of cast copper and the core is filled with lead. Counterweight or Stathmia. Made of stone, lead, glass, and mainly bronze, these were used to weigh goods for sale and coins. Byzantine standard weights followed the Roman duodecimal weight system, in which the main unit was the libra (327.6 gr.). Imperial standard weights were used to verify the weight of gold coins (solidi).