Coining (mint)

Striking a coin refers to pressing an image into the blank metal disc, or planchet, and is a term descended from the days when the dies were struck with hammers to deform the metal into the image of the dies.

Modern dies made out of hardened steel are capable of producing many hundreds of thousands of coins before they are retired and defaced.

Scissel is the scrap produced in the punching of coin blanks from a continuous strip of metal.

Prior to the modern era, coin dies were manufactured individually by hand by artisans known as engravers.

In demanding times, such as the crisis of the Roman Empire in the 3rd century, dies were still used even when they became very worn or even when they cracked.

Experimental archeology suggests that a lower die could be expected to last for up to 10,000 strikes depending on the level of wear deemed acceptable.

[3] Combining archaeological evidence with historic records suggests ancient coin producers (in this case the Amphictions at Delphi) could get as many as 47,000 strikes out of an individual die.

The vast majority of medieval coins were cold struck; the planchets were not heated.

As technology and the economy changed over the course of the Middle Ages, so did the techniques used to create coin dies.

There is evidence of medieval die cutters using engraving tools to lay out designs, and to create detailed punches.

However, engraving on the face of the die did not become commonplace until the early Renaissance.Very detailed records exist for the Venetian mint.

Located in the heart of the city, the Zecca of Venice served as a hub for commercial life and patronage at the time.

On the edge of the US dime, quarter and half dollar, and many world coins there are ridges, similar to knurling, called reeds.

Sometimes these are simple designs like vines, more complex bar patterns or perhaps a phrase, as on the United States dollar coin, on which are the date, mintmark, and motto, E Pluribus Unum.

In addition, the relative positioning between the back and the front can also be used to determine which dies were used for the run that produced a particular coin.

Although the planchet would be softer and more malleable, the extra time and expense would prove too great for the mint.

For example, a doubled die, where a date or another device appears twice slightly offset, is often a highly desired error.

The Bass Foundation has a particularly noteworthy example of an 1806/4 Quarter Eagle ($2.50 gold US coin) in which a piece of the die has broken away, resulting in a heavy rim break over the "LI" in "LIBERTY" on the front.

[8] More typically, a terminal die state will result in crack-like structures appearing on the coin.

[9] This crack-like structure appears like material that is overlaid onto the surface of the coin; this is because the crack on the die allowed the planchet materiel to flow into it during stamping, just like a deliberate design feature.

Some coins exhibit multiple crack-like features, indicating a die that is very close to the end of its serviceable life.

One of the most recent and famous one, is the Austrian 700 Years City of Hall in Tyrol coin, minted on January 29, 2003.