As originally published in Australasian Coin and Banknote Magazine December / January 2020/2021

What Went Wrong -error coins that escaped the mint

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From 1969 to 1984 Australia used the Arnold Machin portrait of Queen Elizabeth II on coins and the distinctive 12-sided dodecagonal shape for the 50c piece. Missing design on this error coin means we cannot be more precise than to date it within this 16 year range.

Weighing in at 8 grams, just over half the mass of a standard 50c (which should weigh 15.55g) this coin is also only about half the thickness that it should be. This is apparent in the dramatic strike weakness seen across both sides of the coin. The legends are missing almost completely around the portrait and the numerals 50 on the reverse are barely visible. It’s interesting to note that weakly struck coins like this one often show better strength of strike in the centre of the coin radiating to more prominent strike weakness at the extremities.

Looking closely at the reverse we can see that the surface of the planchet shows parallel metal striations. This indicates that the cupro-nickel planchet had split in half prior to it being struck. Coin blanks are punched from sheets of metal rolled to the correct thickness. When the blank for this coin was punched out of that metal it contained a flaw in the material that ran parallel to the faces of the blank. At some point after the blank was cut but prior to the coin being struck the coin blank fell in two pieces.

This meant that an approximately half thickness blank was fed into the coin press and when struck considerable strike weakness occurred. This was simply because there was not enough metal to fill the dies for a fully struck coin to emerge.

Coin blanks do fall in half on occasion and it is more common to see a coin split after it was struck. This results in half a coin with one side having a striated appearance and the other side being struck with a design (obverse or reverse) as usual. It is very rare to see an Australian coin such as the 50 cent here struck on a planchet that split before the striking process.

Mark Nemtsas and Kathryn Harris own and run The Purple Penny coin shop in Adelaide and are passionate about error coins.

As originally published in Australasian Coin and Banknote Magazine November 2020

What Went Wrong -error coins that escaped the mint

Australian 1961 Penny with Planchet Hole Error

Not all coin errors that escape coin minting facilities are due to a failure in some part of the mechanical process of manufacturing coins. Sometimes the errors occur because of failures in the metallurgical processes that are required to produce the very metal that coins are made from. The image of the 1961 Perth minted penny shown has a clearly visible flaw caused by (for want of a better term) poor quality bronze.

Coins (generally) are made from metal blanks or planchets. Some of you might be wondering if there is a difference between a “coin blank” and a “coin planchet”, and indeed there is. However, that’s a subject we can cover another time and in this article we’ll use the terms interchangeably. Coin blanks are punched from strips of metal by a machine called a “blanking press”. Those strips of metal should ideally be of uniform width and thickness. Of course, the composition of the metal should also be consistent, but in the case of our 1961Y penny the metal strip the blank was punched from contained what is known as an “inclusion”.

On this coin the inclusion was a metal contamination that was probably an oxide, carbon, or something else like a nitride or a sulphide. The inclusion was embedded in the bronze and at some point while the coin was being made (or perhaps even after it was made) the inclusion has fallen out. On some errors of this type it is possible to determine if the inclusion fell out before or after the coin was struck, but in the case of this error we cannot do so.

A hole is visible right through this coin indicating the inclusion was a thick one. Errors like this penny with a hole through the planchet are very sought after and the bigger the flaw and wider the hole the more desirable they are. Sometimes you’ll see errors of this type with multiple inclusions and we’ve even seen some missing parts of the rim. They are an interesting error type and any serious error collector should look to add one to their collection!

Mark Nemtsas and Kathryn Harris own and run The Purple Penny coin shop in Adelaide and are passionate about error coins.

Originally published in Australasian Coin and Banknote Magazine October 2020

What Went Wrong -error coins that escaped the mint

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Your eyes are not playing tricks on you here, you are indeed seeing double when looking at this 1976 fifty cent coin. Life for this 50c started out just like most others, being struck as normal between an obverse (heads), reverse (tails), and collar die. Events after that point went awry! The coin failed to eject from the press, managing to move a mere 3mm before being struck for a second time. This out-of-collar 2nd strike overstruck and largely obliterated the majority of the first strike.

The first obverse strike is almost invisible under the second strike with just traces apparent around the date and legends and the back of Her Majesty’s portrait. On the reverse it’s much easier to see remnants of the underlying strike. Look at the disjointed appearance of the “50” and the clear remains of the bottom of the central shield. Closer examination of other parts of the reverse design make it apparent that there is a lot of flattening in the design from the second strike due to the placement of metal from the first strike.

Eagle-eyed readers may see that there is also a small strike-through (likely cotton or wire) at the base of Her Majesty’s hair. This coin is a fine example of a double struck Australian fifty cent coin and the authors would like to thank it’s owner for allowing the use the coin’s image in this article.

Mark Nemtsas and Kathryn Harris own and run The Purple Penny coin shop in Adelaide and are passionate about error coins.

As originally published in Australasian Coin and Banknote Magazine September 2020

What Went Wrong -error coins that escaped the mint

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At a passing glance this ‘quaternary alloy’ 1960 florin looks like most of the other 15.76 million minted with that date. This is one of those errors where close examination of the much neglected third side of the coin is required. When this is done it can be seen that this is a special coin indeed.

Australian florins have a reeded or milled edge, a feature originally designed in the middle ages to stop the coin being clipped. However, in more modern times it’s done to stop counterfeiting and to make coins more easily identifiable by touch. The coin edge is struck by the third die (the collar die) and on an Australian florin the edge reeding should extend from the obverse face of the coin to the reverse face. However, it’s obvious from the deformed edge of this coin that an error occurred when it was struck. The planchet only partially engaged with the collar die and thus the edge reeding hasn’t been applied correctly. Consequently, this error type is known as a ‘partial collar error’.

Examination of this particular example shows that the edge milling has been applied to about half the thickness of the coin and the other half is smooth. The milling is present adjacent to the obverse face and not present adjacent to the reverse face. Obviously, the smooth edge is where the coin blank failed to engage with the collar die, indicating that in this case the obverse die was the ‘anvil die’ and the reverse die was the ‘hammer die’. This error can be further classified as a ‘straight partial collar error’ as the transition between the struck / unstruck parts of the rim are parallel to the coin faces. When this transition is not parallel the error is typically known as a ‘tilted partial collar error’.

Mark Nemtsas and Kathryn Harris own and run The Purple Penny coin shop in Adelaide and are passionate about error coins.

As originally published in Australasian Coin and Banknote Magazine August 2020

What Went Wrong -error coins that escaped the mint

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This is just one coin out of a reported mintage of 5.792 million 2005 dated ‘Mob of Roos’ dollars sent into circulation. Without doubt this dollar certainly missed the mark. It’s been struck about 10% or 2-3mm off centre. This type of error coin is known as ‘off centre’ because some of the coin design is missing. On the obverse the top part of the letters “AUST” are missing. On the reverse the three outer kangaroos of the ‘Mob of Roos’ have ears that are partly missing.

How did this mis-strike occur? When the planchet was fed into the coin press it didn’t neatly fall into the collar die as expected and was subsequently struck off centre. The improperly seated blank is then struck unconstrained by the collar die leaving the entire coin out-of-round. Close examination of the base of the letters “AUSTRALI” shows the characteristic ‘V’ shaped indentations known as fishtailing. Fishtailing is an indicator of the metal flowing outward into the void where there was no collar to constrain the strike.

This is not a common error by any means but if you do have a dollar coin that is struck off-centre similar to the coin we’re discussing here then there’s a very high chance it’s dated 2005 as a number of these have been found. Why this many? That is uncertain, but perhaps one or two die pairs were setup incorrectly for the production run. Was there a fault with the coin press? Another possibility is that a group of Type I (un-rimmed) coin blanks were fed into the dies, this being another common reason for off-centre/out of collar strikes.

If you look closely at the cheek of Her Majesty you’ll see a tear shaped die chip. This die indicator is present on a number of similar 2005 ‘Mob of Roos’ errors such as partial collars, broad-strikes and off-centre errors. The authors note that other 2005 errors of a similar type are seen without this die indicator. More research is needed to understand if there were multiple die pairs involved in creating these errors or if it was one die pair deteriorating or malfunctioning through their production life.

Mark Nemtsas and Kathryn Harris own and run The Purple Penny coin shop in Adelaide and are passionate about error coins.