50p error?

[Richard2]

I got these two 50p’s from the bank on different occasions last week and spotted the holes on Queenies chest. Looking more closely with a low powered microscope, they appear to be identical. They don’t look like a centre punch has been used ,but look more like they were done during the minting process. Has anyone else come across this or am I being too hopeful that it’s a genuine error

[Rob]

I'm not sure how you can conclude they were done in the minting process, but would appreciate hearing your reasoning.

I'm going for post mint damage. I would have a guess at it being the result of someone drilling through an object with the 50p being used to protect the work surface. If correct, the two triangular indentations (1st coin by D & 9; 2nd coin by A & E) are most likely from the jaws of the clamp holding the 50p in place.

Alternatively it would have to be due to an object with two triangular feet and a rounded end circular one being forced into the surface of the 50p. I'm not convinced by this one which seems silly.

[Sleepy]

The 2 indentations are caused by someone experimenting with hardness testers the round marks are caused by a Rockwell hardness tester and the triangular by a Vickers hardness tester, you can look up both in Wiki. I suspect some Engineering students playing around in the lab!

Phill

[Richard2]

Not a conclusion Rob just my initial thought. Probably is post mint damage , but why in exactly the same place. And I don’t think the other marks are jaw clamps as you suggest. Too small and not enough of them to be an effective clamp. What I might do is take a centre punch to another 50p and see if I can replicate the marks and the surface finish on the inside of the dents.

[Peckris]

It's not proof, but if you look at the enlargements, the edges to those dents are much sharper than the rest of the coins, which are quite worn. If done at the Mint, the edges would have worn the same amount.

[Richard2]

Good points all three of you, I’ll get me coat

[ShaggyBFC]

12 hours ago, Sleepy said:

The 2 indentations are caused by someone experimenting with hardness testers the round marks are caused by a Rockwell hardness tester and the triangular by a Vickers hardness tester, you can look up both in Wiki. I suspect some Engineering students playing around in the lab!

Phill

Absolutely,  something I did in my 80's apprentice days. We tested every coin just to show the difference in testers and results.