Glossary of Numismatics

Bag Mark: Surface mark, or nick, on a coin usually from contact with other coins in a mint bag. More often seen on large gold or silver coins. Also called "contact marks".
Banker's Mark: A small countermark applied to a coin by a bank or a trader indicating that they consider the coin to be genuine and of legal weight. Most often found on ancient and medieval coins, but also on silver coins which circulated in China and Japan, where they are referred to as chop-marks.
Base metal: Non-precious metal or alloy containing no gold or silver. Common base metals used in coinage include nickel and copper.
Beading: Raised dot border along the rim of a coin.
Billon: Low-grade alloy of gold or silver with a high percentage of another metal, usually copper. Billon is often the result of a sudden debasing of circulating silver coinage due to hyperinflation.
Bi-metallic: A coin with one type of metal in the center with an outer ring of a different metal. An example is the Canadian "toonie" two-dollar coin.
Blank: Prepared disk of metal on which the coin design will be stamped. Also called a 'planchet' or 'flan'. In practice, 'Blank' is also referred to the un-struck or flat side of a uniface coin or medal.
Brass: Copper based alloy with zinc.
Brockage: Originally referring to metal wasted in coin production, now means coins struck when the previous coin remains stuck to a die, creating an incuse impression in the next struck coin (primarily found in ancient coins).
Bronze: Copper based alloy with tin.
Bullion: Precious metals (platinum, gold and silver) in the form of bars, ingots or plate, or where quantity is considered as a valuation. Also refers to coins whose market value is determined by metallic content rather than scarcity.
Bullion Value: Current market value of the raw precious metal content of a coin. For example, the bullion value for Canadian silver coins, 1920 to 1966, is 12 times the face value when silver is $20.00 per troy ounce.