Ceratonia siliqua harubh. "Ceratonia siliqua", the scientific name of the carob tree, derives from the Greek "kerátiοn" κεράτιον 'fruit of the carob (from "keras" κέρας 'horn'), and Latin "siliqua" 'pod, carob'. The unit "carat", used for weighing precious metal and stones, also comes from κεράτιον, as alluding to an ancient practice of weighing gold and gemstones against the seeds of the carob tree by people in the Middle East. The system was eventually standardized, and one carat was fixed at 0.2 grams. In late Roman times, the pure gold coin known as the "solidus" weighed 24 carat seeds (about 4.5 grams). As
Gold coin unveiled in 2012 by the Perth Mint in Western Australia. Known as the "1 Tonne Gold Kangaroo Coin" and with a face value of one million dollars, it contains one metric tonne of 9999 pure gold, and is approximately 80 cm in diameter by 12 cm thick. Other gold bullion coins, many named after their design features, include: Circulating gold coins were usually made of an alloy as other metals are mixed into the coin to make it more durable. Fineness is the actual gold content in a coin or bar and expressed as a "per mil", or thousandths. For