2022 50th Anniversary of the Tamworth Country Music Festival Al Br 50 Cent


Click image to enlarge

Acclaimed as one of the top ten music festivals in the world and Australia’s largest, the Tamworth Country Music Festival celebrated its’ 50th year in 2022. Celebrating this milestone with a commemorative 50 cent struck by the Royal Australian Mint collectors and country music fans can own a golden guitar of their own. Struck on a planchet of golden coloured aluminium bronze the design depicts a guitar in festival lights sculpted by designer Tony Dean. Packaged in a capsule in a bright purple and yellow card this coin has a limited mintage of 30,000. Issue price for this collector coin was $10.

Click image to enlarge

Posted in Collecting Coins

1951 Penny Flaking Planchet Flaw Error


As originally published in Australasian Coin and Banknote Magazine July 2021

What Went Wrong -error coins that escaped the mint

Image 1 – Australia 1951 Penny Flaking Flaw

Collectors of error coins would know that the most common type of pre-decimal coin error is the ‘planchet flaw’. This type of error is also known as a ‘lamination flaw’, ‘planchet peel’, or ‘lamination peel’. Regardless of the name it is caused by some sort of contamination in the metal from which coin blanks are made. Whether the contamination is some sort of gaseous inclusion or a solid impurity like sulphur or carbon the outcome is largely the same, some of the metal in the coin fails to bond correctly to the metal around it.

If this happens to occur near the surface of the coin it can lead to a ‘planchet flaw’ or a region of improperly bonded metal. Sometimes the metallic flaw has fallen off, resulting in a ‘detached planchet flaw’. Other times the metallic flaw remains attached, generally at one end and usually has a flaking appearance. In the case of the 1951 penny shown in Image 1 you can see a large boot-shaped flaking flaw covering nearly a quarter of the reverse. It stands proud of the surface of the coin and is attached on the left side at the kangaroo’s ears. See Image 2 to get an idea of how the flaw protrudes from the surface of the coin.

Image 2 – Australia 1951 Penny Flaking Flaw

Most ‘planchet flaws’ are minor, and in the case of Australian pre-decimal bronze coins, usually found on circulated low grade examples. Sometimes you’ll find one on a high grade penny or half penny, and if large enough they are nice to put into a collection. In the case of the 1951 penny shown here you’ve got the best of both worlds, the coin is a lovely high grade, and the planchet flaw is (and excuse our vernacular), a whopper. We’d be happy to say that this is among the best errors of this type that we’ve seen.

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

Posted in Error Coins

1961 Elliptical Clipped Shilling


As originally published in Australasian Coin and Banknote Magazine June 2021

What Went Wrong -error coins that escaped the mint

Figure 1 – Australia 1961 Shilling Elliptical Clip Error – Obverse

In this article we showcase an unusually shaped 1961 shilling which at first glance appears to be a cut down coin. However, close examination of the coin shows that it is indeed a genuine mint error. What aspects of the coin should you, the error coin collector, examine to distinguish this coin from a damaged one? Three key points of interest are below:

1. Examine the bases of the legend lettering near the missing areas of the coin. They should show the characteristic ‘fish tail’ appearance that is a sign of unconstrained radial metal flow. The letters TIA REGIN of GRATIA REGINA clearly show this on the obverse.
2. Do the design elements near the missing areas of the coin appear to be “falling” toward the edge of the coin? This is another sign of unconstrained metal flow. Note on the reverse how the arms of the star are bending toward the rim of the coin.
3. Look at the transition from areas of fully struck up rim to poorly struck up rim. A genuine error should show a gentle flowing transition rather than a harsh or sharp transition. The rim near D: + at the top of the obverse is fully struck and smoothly transitions clockwise as it becomes more and more weakly struck.

Figure 1 – Australia 1961 Shilling Elliptical Clip Error – Reverse

There are other elements on this coin that prove its authenticity but the three points above are the most important.

Of course we haven’t classified this error yet. There’s a clue in the shape of the coin which allows us to call it an Elliptically Clipped Planchet Error. The error has come about due to a failure in the process that punches out coin blanks from a metal strip, leading to an incomplete planchet being struck. The Elliptically Clipped Planchet Error is probably the second hardest clipped planchet error to find, and if you ever have the chance to purchase one at a reasonable price you should do so. You’re unlikely to see another one any time soon!

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

Posted in Error Coins

1966 10 Cent Upset Error

As originally published in Australasian Coin and Banknote Magazine May 2021

What Went Wrong -error coins that escaped the mint

Australia 1966 10 Cent Error Struck with Upset Dies

Let’s play a game! Take an Australian coin out of your purse or wallet and hold it by the edges with your forefinger at the top, your thumb at the bottom and the portrait of the Queen upright. Spin the coin between your fingers so the tails side is facing you. What you’ll be looking at now is the tails side of the coin the right way up. That’s because Australian Coins (but not all coins) are struck in what is known as “medal orientation”. That’s just a fancy way of saying the head and tails side of a coin are the same way up!

Very occasionally obverse or reverse coin dies may not be oriented correctly when striking coins. This might have been due to an installation error, an error in the coin die hubbing process, or perhaps a mechanical failure. Coins struck from mis-oriented dies result in what is known as “rotated die” or “upset die” coin errors where the obverse and reverse designs of the coin are not oriented correctly. In the image shown here you can see one of the better-known upset coin errors in the Australian coin series, the 1966 10 cent coin.

During the production run of one pair of dies striking 1966 10 cents struck at the Royal Mint in London the obverse die was loose and rotated continually as coins were struck. As a result, upset or rotated die 1966L 10 cent coins have been found in many different degrees of rotation. This can be labelled as degrees or angles of the clockface. The error shown here is an almost perfect 180 degree or 6 o’clock rotation. You might be wondering how we know it was the obverse die that was moving and not the reverse? That’s because the edge reeding on all the upset 10 cent coins we’ve observed is fixed relative to the reverse design, but not the obverse. Which indicates a moving obverse die!

This type of error is the most easily overlooked but as a collector it’s one you can look out for and may still find in your purse or wallet even after 55 years in circulation.

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

Posted in Error Coins

1966-1984 2 Cent Off Centre Strike Error

As originally published in Australasian Coin and Banknote Magazine April 2021

What Went Wrong -error coins that escaped the mint

Australia 1966-1984 2 Cent Off Centre Error

If you’re new to coin collecting or just new to error coins then the ‘off centre’ coin error is among the most instantly recognisable. As well as being distinctive, they are extremely desirable because it’s so obvious what has gone wrong with them! The coin in the image seen here is an Australian 2 cent that has been struck 40% off centre. 40% of the coin remains unstruck while 60% of the design is present. We’re not sure of the date (because the date is missing) but the Arnold Machin portrait of Queen Elizabeth II places it somewhere from 1966 to 1984.

This error two cent coin was produced when the blank planchet entered the coin press while the collar die failed to engage. The collar die is the third die that holds the planchet and if required, applies any edge milling. The coin blank was not located properly (perhaps due to the lack of the collar die engagement) and when struck was several millimeters away from where it should have been. This gave us our off-centre strike. How do we know the collar die was not engaged? Primarily because the coin is flat without any noticeable step in it.

What makes an off-centre strike a more desirable error to own? There’s a number of factors which of course include grade and condition. Another major factor is how far off centre the error is and generally the further off centre the more desirable it becomes. The final factor is the denomination as this usually dictates the scarcity of errors. In the Australian decimal series $1, $2, and 50 cent off-centres are the most sought after. This is followed by 20 cent, 10 cent and the remaining three smaller denominations more commonly found.

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

Posted in Error Coins

1953-1964 Half Penny Die Adjustment Strike Error

As originally published in Australasian Coin and Banknote Magazine March 2021

What Went Wrong -error coins that escaped the mint

Australian 1953-1964 Half Penny Die Adjustment Strike

The accompanying image shows an Australian coin, half penny in size and weight, that is missing almost all the design around the edges of the coin. It has almost no trace of the legends apparent. The keen-eyed observer may also note that the portrait of the Queen and the kangaroo are very weak and incomplete. Why is this the case? It’s a simple enough explanation, the coin was struck with a much lower pressure than that required to produce a fully struck up design. The next (and obvious question) is HOW did it get struck with such a low pressure? That’s a more difficult question to answer precisely. Before we address that we’ll look at a couple of other characteristics of this coin that gives us interesting insights into the coin production process.

Firstly, how do we know this error coin that escaped the mint is actually due to a low-pressure strike and not a filled die? The primary indicator is the consistency of the quality and strength of the strike across each side of the coin and when comparing the two sides to each other. Notice how both sides are (relatively) strongly struck in the centres and the quality of strike gradually weakens out toward the edges of the coin. Filled dies tend to show random changes in strike strength depending on where the die is filled while weak strikes show the gradual change in strike strength seen here.

Secondly, WHY does the coin appear more strongly struck in the centres and not struck at all around the edges? That’s because often coin dies are not flat! They are ever so slightly dome shaped with the highest portion in the centre and the lowest at the edges. As a result, extreme weak strikes like this half penny show the strike characteristics you can see so clearly here.

What is the name for this type of error? Typically, you’d see it labelled as a “die adjustment strike”. This suggests that it was produced deliberately during the coin press setup process and the die striking pressure was being adjusted or ‘dialled in’ to create coins that are properly struck up, but not struck so strongly that the life of the coin dies is reduced. Of course, if striking pressure was reduced accidentally (due to a machine failure for example) exactly the same type of error coin would be produced. Whether we call this handsome half penny a “die adjustment strike” or a “weak strike” it’s an impressive coin error well worth seeking out!

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

Posted in Error Coins

1988 10 Cent Struck on 2 Cent Planchet

As originally published in Australasian Coin and Banknote Magazine February 2021

What Went Wrong -error coins that escaped the mint

Australian 1988 10 Cent Struck on 2 Cent Planchet

Leave an Australian copper nickel coin (5c, 10c, 20c, or 50c) lying on the ground for several months or years or perhaps bury it for some time and it will often tone a distinctive brown earthy colour. On first glance the coin shown here has this type of colouring and perhaps it would be spent by a member of the public without too much thought. This coin is quite different though, it is clearly uncirculated and shows considerable mint bloom, similar perhaps to a bronze coin. We knew it was something special and an XRF test confirmed that this coin was not struck on a cupro-nickel blank but in fact a copper alloy blank intended for two cent pieces.

The coin weighs in at 5.16g well within tolerance of the nominal weight of a two cent coin. This is exactly half a gram less than a regular 10 cent coin. Could a 2 cent blank be struck by ten cent dies? The diameter of a 2c is about 2mm less than a 10 cent, so yes, a 2 cent blank could fit into the collar die intended to mint a 10 cent coin and be struck. But of course, the lower mass and smaller diameter would give rise to key indicators in the strike of the coin. Are these indicators present? Yes, indeed they are.

The obverse legends in particular ABETH II of ELIZABETH II exhibit fishtailing of the lettering, this is a sure sign of unconstrained radial metal flow due to the small blank not filling the collar entirely prior to being struck. You’ll also note that the rim is not fully formed for about one third of the circumference of the coin. This is another sign that the blank was both undersized and underweight. Sadly scratches on the reverse are tell-tales that this coin may have failed to exit the coin press and was helped along the way by an eager mint technician with a metal tool of some sort.

Wrong planchet errors are always highly sought after by collectors. Wrong planchet, off-metal errors are more visually appealing because they are obviously the wrong colour. Underweight, wrong planchet, off-metal errors are even more desirable because of the distinctive qualities of the strike that help establish their authenticity. This 1988 10c struck on a 2c blank fits all these criteria nicely and as such is a very desirable coin. Eagle-eyed readers might have noted a small cud on the top lip of the Queen’s portrait. This may allow the fastidious collector to find a regular copper nickel 1988 10 cent struck from the very same dies as this spectacular error. That would be a fine pair of coins to own!

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

Posted in Error Coins

Australian Decimal Coin Weight Tolerances

How much does my coin weigh? This is a common question first asked when a coin seems not quite right. Is it an error coin? Is the coin missing design or a part of the coin? Does it feel lightweight or too heavy? Does it sound different when dropped on the bench? Does the metal it’s made from appear different to normal? A coins weight must be accurately measured on a scale ideally to 2 decimal places. This is usually done a jewellers scale.

A coin has a legal parameter that it fits with regard to weight. A normal weight can differ up or down and still fit into the tolerance for a genuine coin. It can be handy to know these allowable tolerances as we examine coins closely. This is why we’ve compiled this handy guide to help collectors out. Information derived from Australian Currency Determinations for legal currency.

Decimal Coin Tolerances

CoinStandard Design Metal Composition ShapeEdgeDiameter (max) mmThickness (max) mmWeight gramsWeight Tolerance gramsWeight Minimum gramsWeight Maximum grams
1 Cent (1c) Feather Tailed Glider 97% Copper, 2.5% Zinc , .5% Tin Round Plain 17.75 1.80 2.60 +/- 0.3 2.30 2.90
2 Cent (2c) Frill-Necked Lizard 97% Copper, 2.5% Zinc , .5% Tin Round Plain 21.80 2.20 5.20 +/- 0.3 4.90 5.50
5 Cent (5c) Echidna 75% Copper, 25% Nickel Round Milled 19.53 1.90 2.83 +/- 0.33 2.50 3.16
10 Cent (10c) Lyrebird 75% Copper, 25% Nickel Round Milled 23.82 2.30 5.65 +/- 0.49 5.16 6.14
20 Cent (20c) Platypus 75% Copper, 25% Nickel Round Milled 28.65 2.92 11.30 +/- 0.78 10.52 12.08
50 Cent (50c) Coat of Arms 75% Copper, 25% Nickel Dodecagon (12 sided) Plain 31.65 3.16 15.55 +/- 0.96 14.59 16.51
One Dollar ($1) Mob of Kangaroos 92% Copper, 6% Aluminium, 2% Nickel Round Interupted Milled 25.20 3.46 9.00 +/- 0.66 8.34 9.66
Two Dollar ($2) Aboriginal Elder 92% Copper, 6% Aluminium, 2% Nickel Round Interupted Milled 20.62 3.70 6.60 +/- 0.6 6.00 6.60


Posted in Collecting Coins

1969-1984 50c Struck on Underweight Split Planchet

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

What Went Wrong -error coins that escaped the mint

Click image to enlarge

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.

Posted in Error Coins

1961 Penny with Planchet Flaw / Hole

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.

Posted in Error Coins

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