QUIZ: Marks found on coins.
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  1. IMG_4620.JPG This micrograph shows the chin and field under the chin of a Morgan dollar. Both the relief design of the chin and the flat field under the chin have two different types of marks INTO the coin's surface. What caused each?
     

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Insider, I know you like colors so I circled what I see:

Red: deep marks in random patterns, most likely contact marks (bag marks, etc - normal hits)
Orange: thin, whispy long lines, most likely from polishing, a wipe, or potentially cleaning (need to see the rest of the coin to confirm)
Purple: deep marks in what appears to be a regular pattern. Could be dentil marks (reed marks) from contact with another coin.
Pink: Long, thin, straight, regular lines. Potentially roller marks.
Blue: short, intermittent parallel marks. I'll be honest, I'm stumped on this one. Perhaps seeing more of the coin might help.
Green: very small, random pattern, scattered across the surface of the coin. Three thoughts on this one, would need to see the rest of the coin and luster to confirm. First, and most likely thought, is some sort of planchet flaw. I've seen the fields of coins where it looked like the planchets had been very roughly tumbled but not polished, and the force of striking didn't completely removed the roughness. It could also be something raised on the surface of the die - pimples from die rust that hadn't been removed. Depending on the mint, rust was a common issue. Third thought, it could be where some corrosion was starting to form on the surface of the coin, eating into it, and the corrosion was removed. I think this is the least likely, because it looks like contact marks are over the top of this area - removal of corrosion indicates it was conserved, and I would hope that a collector would not then cause a huge mark like that.

Well, I'm hoping I got at least some of them right!

img_4620-jpg.1181358

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The marks on the chin (blue circle by Jason) look to be indentations that appear to be evenly spaced in a pattern with a flat top edge and a rounded at the bottom of each mark.  I don't know what caused it, but it seems to be either the coin was stamped with something or grabbed and moved by something that had protruding bumps like on a conveyer belt.  Perhaps some sort of old time coin counting machine used in banks or casinos for slot machines.

The marks in the field below the chin (green circle by Jason) are much finer and not in any pattern and don't look like bag marks.  Looks like someone shot it with a really tiny shotgun.  I have no idea what caused these marks.

Edited by lehigh96
add reference to Jason's circles

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9 minutes ago, lehigh96 said:

 grabbed and moved by something that had protruding bumps like on a conveyer belt.  Perhaps some sort of old time coin counting machine used in banks or casinos for slot machines.

I usually associate counting machine marks with circular patterns, but your theory does make sense.

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1 minute ago, physics-fan3.14 said:

I usually associate counting machine marks with circular patterns, but your theory does make sense.

Yeah, no way it could be a modern counting machine, I'm thinking something from the late 1800's or early 1900's that required manual manipulation rather than electricity.

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If it were a gold coin, my answer would be quite different for one of them: the marks in the green circle look like "sweat marks" I've seen on gold coins, where a few coins are put in a bag and shaken to knock of micro bits of gold, and then that's collected and the coins are returned to circulation. The gold dust is profit. As far as I know, I don't think I've seen silver coins subjected to that.

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well, this is intriguing.

I can do nothing but guess on this one. I see what looks like corrosion but only in the field. i see what looks like marks from other coins but only on the device. I can give no intelligent guesses. 

 

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The blue and the green circles are the subject of the quiz.  We'll talk about the other circles later.

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The blue ones are roller marks; the green ones are from being left in a dip for too long.

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Insider posted the answers over on coin talk. He claims that the marks in the field are struck through sawdust. I am skeptical of that claim. However, he has no idea what the marks are on the face.

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The marks on the devices(Liberty's cheek), anything could have made those.  The marks under her chin, in the fields, looks like corrosion.  I thought about struck through debris also.  But, it looks more like corrosion to me with a dip.

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21 minutes ago, physics-fan3.14 said:

Insider posted the answers over on coin talk. He claims that the marks in the field are struck through sawdust. I am skeptical of that claim. However, he has no idea what the marks are on the face.

Funny, silly and a little sad. Small particles are more likely to collect in recesses of the die - Liberty's neck, for example. If they were stuck to a planchet, the sharp boundary shown on the coin is highly unlikely - especially after all the jiggling, rolling, turning, sliding, etc. that occurs before the planchet come to rest on the lower die. Sawdust is fluffy and highly compressible, unlike some types of solid wood. But, even the hardest solid wood leaves a smooth-edge impression on coin silver/gold. Compare with coins where a metal wire has been on the planchet - they do not produce the same surface deformation.

(The Philadelphia Mint bought only hardwood sawdust from mills in the Philadelphia area. It was used very sparingly and recycled many times. Soft woods contained resins which would discolor planchets.)

A coin spends nearly all of it's "life" in a bag of other coins - until it is released into the wild to explore the world. Most Uncirculated coin marks are caused by contact with other coins and sometimes with equipment. Once out of the bag, anything can happen.

Edited by RWB

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Sorry, I got busy.  The marks under the chin are strike thru's - probably sawdust from drying the planchet.  For those who believe that is not the case, then someone threw a sack of dirt on to the die!   because Note that one of the marks on the coin has already been answered.

As for the other set...the parallel dashes on the chin. I DON'T KNOW WHAT CAUSED THEM! :facepalm::jawdrop::hilarious::hilarious::hilarious::hilarious:

Here is what we know. They are into the surface and uniform. They are in a flat plain and are fairly common if you look at enough coins - especially dollars. They can be on the relief as in this case or in the field. They are not PMD! They have the same color inside the mark as a struck thru SO THEY WERE ON THE PLANCHET and not struck out when the coin was made. Therefore, they are planchet defects of some kind.

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3 hours ago, Coin Cave said:

The marks on the devices(Liberty's cheek), anything could have made those.  The marks under her chin, in the fields, looks like corrosion.  I thought about struck through debris also.  But, it looks more like corrosion to me with a dip.

Corrosion?  The marks are into the coin so we know the die was not corroded because ________.  If the coin were corroded, the surface would be damaged (etched) once the corrosion products were removed.   The pits into this coin under the chin are "pristine." They have the same surface as an unstruck planchet.  When bits of sawdust are removed from the surface of a coin, the marks left behind look exactly as this.  Burn it into your mind for when you see it again in the future.

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3 hours ago, RWB said:

Funny, silly and a little sad. Small particles are more likely to collect in recesses of the die - Liberty's neck, for example. If they were stuck to a planchet, the sharp boundary shown on the coin is highly unlikely - especially after all the jiggling, rolling, turning, sliding, etc. that occurs before the planchet come to rest on the lower die. Sawdust is fluffy and highly compressible, unlike some types of solid wood. But, even the hardest solid wood leaves a smooth-edge impression on coin silver/gold. Compare with coins where a metal wire has been on the planchet - they do not produce the same surface deformation.

(The Philadelphia Mint bought only hardwood sawdust from mills in the Philadelphia area. It was used very sparingly and recycled many times. Soft woods contained resins which would discolor planchets.)

A coin spends nearly all of it's "life" in a bag of other coins - until it is released into the wild to explore the world. Most Uncirculated coin marks are caused by contact with other coins and sometimes with equipment. Once out of the bag, anything can happen.

The only thing SAD in this thread was your usual lame attempt at humor on Monday by posting a rock!   (tsk)   

"Small particles are more likely to collect in recesses of the die."  100% in agreement except these are not made by small particles - the black or clear gunk on the dies and press that contains micro-particles of coinage alloys.  

"...the sharp boundary shown on the coin is highly unlikely ".  Disagree 100%. A struck thru mae by a soft substance (grease, cloth) has a rounded border.  A struck thru from a hard substance has a sharp border as this.  The inside of a strike thru often leaves an impression of what made it; however, most of the time it is just smooth as you posted.  

"The Philadelphia Mint bought only hardwood sawdust from mills in the Philadelphia area."  Nice to know but so what?

"Most Uncirculated coin marks are caused by contact with other coins and sometimes with equipment."  I agree 100%.  Knowledgeable numismatists know the difference between a contact mark into a coin (DAMAGE to its surface) and a pristine as struck totally original area caused by a planchet defect.  The purpose of this "quiz" was to show the characteristics of a struck thru in one case and see if anyone knew what caused the dash-marks in the other.   

Edited by Insider

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RE: ""...the sharp boundary shown on the coin is highly unlikely ".  Disagree 100%. A struck thru made by a soft substance (grease, cloth) has a rounded border.  A struck thru from a hard substance has a sharp border as this.  The inside of a strike thru often leaves an impression of what made it; however, most of the time it is just smooth as you posted."

No....we agree.  What was called "sawdust strike through" appears to have soft borders and incuse detail - exactly as you explained immediately above.

Hardwood solid bits or shavings will, under rapid, extreme pressure, behave more like a metal. (Much the same as landing on water from a height of 2-feet and 200-feet.) Cellulose cell walls are amazingly robust - just ask any concrete wall with a 2x4 driven through it by tornado winds.

Material performance under high pressure - especially rapid application of force - was far beyond anything researched by the US Mint. However, the Royal Mint took great interest in the subject. This was led by Sir William Chandler Roberts-Austen, "Assistant to the Master of the Mint and then Chemist of the Royal Mint (1869), Professor of Metallurgy at the School of Mines (1880), and Chemist and Assayer to the Royal Mint (1882–1902). He developed procedures for the analysis of alloy constituents and an automatic recording pyrometer used to record temperature changes in furnaces and molten materials. He was the singular world authority on the technical aspects of minting coins. His work had many practical and industrial applications."

 

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24 minutes ago, Insider said:

"...the sharp boundary shown on the coin is highly unlikely ".  Disagree 100%. A struck thru mae by a soft substance (grease, cloth) has a rounded border.  A struck thru from a hard substance has a sharp border as this.  The inside of a strike thru often leaves an impression of what made it; however, most of the time it is just smooth as you posted.  

I think you misunderstand what Roger is saying. I think what he means is - its unlikely for a strikethrough like this (sawdust) to be only in the fields and abruptly stop right at the edge of the neck. Its far more likely that it would carry over onto the neck. 

4 hours ago, RWB said:

But, even the hardest solid wood leaves a smooth-edge impression on coin silver/gold.

And this is why I'm skeptical of the sawdust theory. 

Edited by physics-fan3.14

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Oh...OK... "I think you misunderstand what Roger is saying. I think what he means is - its unlikely for a strike through like this (sawdust) to be only in the fields and abruptly stop right at the edge of the neck. Its far more likely that it would carry over onto the neck."

I misunderstood the misunderstanding or what Insider understood of what I wrote about understanding, ehhhhh....yeah, OK.

Yes. I agree with physics-fan 3.14. That is the idea I meant to convey.

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15 hours ago, RWB said:

RE: ""...the sharp boundary shown on the coin is highly unlikely ".  Disagree 100%. A struck thru made by a soft substance (grease, cloth) has a rounded border.  A struck thru from a hard substance has a sharp border as this.  The inside of a strike thru often leaves an impression of what made it; however, most of the time it is just smooth as you posted."

No....we agree.  What was called "sawdust strike through" appears to have soft borders and incuse detail - exactly as you explained immediately above.

Hardwood solid bits or shavings will, under rapid, extreme pressure, behave more like a metal. (Much the same as landing on water from a height of 2-feet and 200-feet.) Cellulose cell walls are amazingly robust - just ask any concrete wall with a 2x4 driven through it by tornado winds.

Material performance under high pressure - especially rapid application of force - was far beyond anything researched by the US Mint. However, the Royal Mint took great interest in the subject. This was led by Sir William Chandler Roberts-Austen, "Assistant to the Master of the Mint and then Chemist of the Royal Mint (1869), Professor of Metallurgy at the School of Mines (1880), and Chemist and Assayer to the Royal Mint (1882–1902). He developed procedures for the analysis of alloy constituents and an automatic recording pyrometer used to record temperature changes in furnaces and molten materials. He was the singular world authority on the technical aspects of minting coins. His work had many practical and industrial applications."

 

Let's just blame my poor images.   I'll find some magnified images of sawdust.

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15 hours ago, physics-fan3.14 said:

I think you misunderstand what Roger is saying. I think what he means is - its unlikely for a strikethrough like this (sawdust) to be only in the fields and abruptly stop right at the edge of the neck. Its far more likely that it would carry over onto the neck. 

And this is why I'm skeptical of the sawdust theory. 

You are correct.  There are some identical patches on the relief.

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15 hours ago, RWB said:

Oh...OK... "I think you misunderstand what Roger is saying. I think what he means is - its unlikely for a strike through like this (sawdust) to be only in the fields and abruptly stop right at the edge of the neck. Its far more likely that it would carry over onto the neck."

I misunderstood the misunderstanding or what Insider understood of what I wrote about understanding, ehhhhh....yeah, OK.

Yes. I agree with physics-fan 3.14. That is the idea I meant to convey.

I misunderstood when I read what was misunderstood by you and the misunderstanding was explained due to my misunderstanding of the misunderstood explanation. :)

 

Image3.jpg

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Thanks! I misunderstand what was misunderstood, completely.

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PS: Good thing Morgan's wife - who resembles the dollar coin portrait - wasn't a teen bride. We might have had intentional pimples on her cheek.

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Image3.jpg

 

A man is walking in the dark with a sandstorm going on and he bumps into what he thinks is the entrance to a small cave.  He falls asleep to wait out the storm and wakes up under this thing.  Gulp.  

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...and he made it through the storm unharmed. Cool Beans! He then finished his journey well rested

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