The expression Siliqua (Latin: pod) comes from the siliqua graeca , the seed or the pod of the carob tree . According to the Roman weight system, this weighed 1/6 of the sextula (1/144 of the Roman ounce) or approximately 0.19 grams . The term was used for various silver coins that were supposed to be 1/24 of the value of a gold solidus . However, since gold was worth around 14 times as much as silver in ancient Rome, such a silver coin should theoretically have weighed 2.7 grams. Nevertheless, the term was first used for silver coins in 320 under Emperor Constantine the Great . These coins initially weighed 3.4 grams, but their value soon declined due to inflation. The Siliqua was therefore later reassessed by Emperor Constantine II and reduced by 1/3. The "new" Siliqua weighed about 2.2 grams.
The term "Siliqua" is used because no name has been passed down for these coins from contemporary sources. In numismatics , thin silver coins from the time up to the 7th century, weighing between 2 and 3 grams, are called siliqua. The double siliqua was at times called the maiorina .