Coins Treasure World: 06 Coinage metals

Coins are made from one or more coinage metals.

Many coinage metals (or alloys) are from the three nonradioactive members of Group 11 of the Periodic table (copper, silver and gold); however there are many, even for coins made from intrinsically precious metals. Precious metals are always used in bullion coins and some collectable coins. Coins not intended for circulation or for intrinsic value have also been made experimentally using an even larger variety of metals, since they function as fiat money. In general coins intended for circulation must have metal values considerably less than their face values, for reasons discussed below.

Group 11 Elements :

Copper
Cu
Atomic Number:	29
Atomic Weight:	63.546
Melting Point:	1357.75 K
Boiling Point:	2835 K
Specific mass:	8.96 g/cm3
Electro negativity:	1.9

Silver
Ag
Atomic Number:	47
Atomic Weight:	107.8682
Melting Point:	1234.15 K
Boiling Point:	2435 K
Specific mass:	10.501 g/cm3
Electro negativity:	2.2

Gold
Au
Atomic Number:	79
Atomic Weight:	196.966569
Melting Point:	1337.73 K
Boiling Point:	3129 K
Specific mass:	19.282 g/cm3
Electro negativity:	2.54

Fiat money is money that has value only because of government regulation or law. The term derives from the Latin fiat, meaning "let it be done", as such money is established by government decree. Where fiat money is used as currency, the term fiat currency is used. Today, all national currencies are fiat currencies, including the US dollar, the euro, and all other reserve currencies.

Coins that are intended for circulation have some special requirements based on the conditions they will encounter. For example, a coin may be in circulation for up to 30 years, and so must have excellent wear resistance and anti-corrosion properties. Achieving this goal necessitates the use of base metal alloys. Some metals like manganese have occasionally been used in coins, but suffer from making the coins too hard to take an impression well (or metals apt to wear out stamping machines at the mint).

A common base metal alloy for everyday coinage is Cupro-Nickel (also cupronickel), with varying proportions of copper and nickel. Cupronickel has a silver color, is hard wearing and has excellent striking properties, essential for the design of the coin to be pressed accurately and quickly during manufacture.

When minting coins, especially low denomination coins, there is a risk that the value of metal within a coin is greater than the face value. This leads to the possibility of smelters taking coins and melting them down for the scrap value of the metal. Pre-1992 British pennies were made of 97% copper; but as of 2008, based on the price of copper, the value of a penny from this period is 1.5 new-pence. Modern British pennies are now made of copper-plated steel. For similar reasons, American pennies (cents) were once made of copper alloys, but since 1982 have been made of copper-clad zinc.

01 Numismatist’s Vision