Can 90% Gold Be Scratched with a Fingernail?

[QuantumTheory]

I'm not chemist, but I know a bit about the elements. I have a rock book which tells about the different gems and rocks, under gold, it is you cannot scratch gold with your fingernail, but with a knife.

I recently bought a 90% gold (10% alloyed with other harder metals) gold lucky angel. When it I got it it wasnt as good as condition in the picture, and it had a black mark on it, possibly a scratch that was filled in. I tried to rub it off with my fingernail, and got it into an argument to whether you can scratch 90% gold with your fingernail. I HIGHLY DOUBT this is possibly, granted, my rock book told me it wasn't possible, secondly, this isn't pure gold. It is alloyed with other metals, which makes it harder. Here's what he said:

"And you wonder why people become frustrated with you ?

I am well versed with the Periodic Table. I am also well versed with
gold coins - both pure and alloyed. And they can both be scratched with a
fingernail. For that matter, any coin - gold, silver, copper, nickel,
aluminum etc etc etc can be scratched with your fingernail.

Remember when I told you I would give you facts ? Those are facts !"

What do you thikn of this?

 

[QuantumTheory]

Oh yeah, I bet he's not wel versed as wel as you people are!

 

[QuantumTheory]

These coin people, are so into the hobby, numismatics, that they are blind in some ways. They think you can scratch a coin anyway, even one made out of titanium. Its lame

 

[Gokul43201]

I guess it depends on what his fingernails are like. Who knows; they may be special !

 

[Entropy]

Yeah, but the scratchs are mircoscopic.

 

[QuantumTheory]

Yeah, but the scratchs are mircoscopic.

EXACTLY! How microscopic though? 30x? higher?

my point, LOL I agree

what about scratching NICKEL with your fingernail? Can you do that too? :rofl:

 

[QuantumTheory]

I guess it depends on what his fingernails are like. Who knows; they may be special !

IMHO, they'd have to be VERY special to scratch gold alloyed with other stronger metals, or for heaven sakes, NICKEL! Of course I could be wrong, which is why i wanted to talk to you smart chemist folks

:)

 

[Gokul43201]

I share the same opinion (alloying gold with almost anything will only make it harder) as you, but the only way to really tell is by trying it.

You've got a gold coin handy...you tell me !

 

[QuantumTheory]

I share the same opinion (alloying gold with almost anything will only make it harder) as you, but the only way to really tell is by trying it.

You've got a gold coin handy...you tell me !

Hmm, I did and my mom did actually to try and remove this black stuff from the coin. I didn't see any noticable scratch with the coin, and if there was any, it was microscopic.

But generally its not good to try and scratch your coin in ANY WAY even with your fingernail, as if it does scratch it, (And if you can see the scratch under 10x magnication) this will reduce the grade drastically, thus decreasing the value.

 

[QuantumTheory]

Damn does no one really know?

 

[QuantumTheory]

Damn does no one really know?

 

[jimmie]

I would try, but I haven't even got 2 nickels to rub together.

 

[Gokul43201]

Pure gold has a Vickers hardness of 25 (VHN). Keratin has a VHN value that is usually between 10 and 20, but could, in exceptional cases exceed 25, I guess. So, it might be possible to scratch pure gold with a fingernail.

Nickel and Copper (dep[ending on the alloy and heat treatment) have hardness values ranging typically around 75 - 100. There's no way to scratch them by a fingernail (unless your fingernail has some hard "microcrud" stuck in it).

 

[QuantumTheory]

Pure gold has a Vickers hardness of 25 (VHN). Keratin has a VHN value that is usually between 10 and 20, but could, in exceptional cases exceed 25, I guess. So, it might be possible to scratch pure gold with a fingernail.

Nickel and Copper (dep[ending on the alloy and heat treatment) have hardness values ranging typically around 75 - 100. There's no way to scratch them by a fingernail (unless your fingernail has some hard "microcrud" stuck in it).

As someone said earlier, would it possible to see a minor scratch with your fingernail to these coins under a 30x microscope or 10x magnifcation?

Pure gold can be scratched by a fingernail. But I'm talking about .900 fine gold or 90% gold 10% other metals for hardness.

This person said ALL metals in coins can be scratched by your fingernail. Do you know how many metals were made from coins? Anything from lead to titanium! Tons of alloys were used

 

[QuantumTheory]

"GCL(me) i told you ages ago that GD is the most knowledgeable guy around here when it comes to gold coins. If you won't listen to him then who will you listen to?"

 

[QuantumTheory]

Pure gold has a Vickers hardness of 25 (VHN). Keratin has a VHN value that is usually between 10 and 20, but could, in exceptional cases exceed 25, I guess. So, it might be possible to scratch pure gold with a fingernail.

Nickel and Copper (dep[ending on the alloy and heat treatment) have hardness values ranging typically around 75 - 100. There's no way to scratch them by a fingernail (unless your fingernail has some hard "microcrud" stuck in it).

Ooh, we got someone who thinks he knows better now Gokul. This is what he said:
"LOL this is too funny. Haven't you heard of something called Moh's
hardness scale? Gold's hardness is around 2.5 and copper is around 3.0. We
all should know that diamond is the hardest at 10.Your fingernail
whereas has a hardness of 2.5 to 3.0 at maximum if you try really hard.
Conclusion? Gold and copper CAN be scratched. Gold alloy? You should know
the story. Gold alloy just got harder in between 2.5 to 3.0. Of course,
a steel knife can wreck a gold coin easily - it has a hardness of 5.5
to 6. A gold alloy wouldn't be able to stand against it.

If you don't believe this, you can check wikipedia or other links. Just
don't tell me that your book tells me this is wrong or that is wrong.
PROPER facts please. If you hate to believe every single word I said,
you can always do an experiment, especially the highest raised point.
That will ruin your coin easily and if you are to be clever enough, you
ought to researching harder instead of asking lame questions. Or unless
you have the funds to waste. Add another lame "fact" and I (or someone
else) will be here to troll every single one that you make until you
recognize that you made a fatal mistake.

Honestly, I am sick to read how you are coming out with ridicious
"facts" and by claiming that you know this by adding that you have dealt
with gold for so long. It doesn't matter HOW LONG you know, it only
matters HOW WELL you know. And to add another fact, you seriously don't know
everything. As a keypoint, you didn't even bother to think about or
didn't even know such scale existed. If you wondered where those crap came
from, it originated from a geological-chemistry aspect.

>>You still have a lot to learn.<<

If you still want to doubt the whole thing, go ahead. Please troll my 3
year study in geochemistry. And if that isn't good enough for you, you
can write to my dad who has been in the precious metal plating industry
for over 30+ years. And I can bring more people in if you wish to know
the real truth.
"

 

[QuantumTheory]

Ok this is really pissing me off now..

Mr.Bigguy is bragging about his knowledge of chemistry at the coin forums. He says you can scratch gold alloyed with other metals with your fingernail. He brags about his 50+ years in geochemistry. Talk about an ego. God I hope they ban me from that forum, its supposed to be family friendly.

Here's what he said:
"Ooh, we got someone who thinks he knows better now Gokul. This is what he said:
"LOL this is too funny. Haven't you heard of something called Moh's
hardness scale? Gold's hardness is around 2.5 and copper is around 3.0. We
all should know that diamond is the hardest at 10.Your fingernail
whereas has a hardness of 2.5 to 3.0 at maximum if you try really hard.
Conclusion? Gold and copper CAN be scratched. Gold alloy? You should know
the story. Gold alloy just got harder in between 2.5 to 3.0. Of course,
a steel knife can wreck a gold coin easily - it has a hardness of 5.5
to 6. A gold alloy wouldn't be able to stand against it.

If you don't believe this, you can check wikipedia or other links. Just
don't tell me that your book tells me this is wrong or that is wrong.
PROPER facts please. If you hate to believe every single word I said,
you can always do an experiment, especially the highest raised point.
That will ruin your coin easily and if you are to be clever enough, you
ought to researching harder instead of asking lame questions. Or unless
you have the funds to waste. Add another lame "fact" and I (or someone
else) will be here to troll every single one that you make until you
recognize that you made a fatal mistake.

Honestly, I am sick to read how you are coming out with ridicious
"facts" and by claiming that you know this by adding that you have dealt
with gold for so long. It doesn't matter HOW LONG you know, it only
matters HOW WELL you know. And to add another fact, you seriously don't know
everything. As a keypoint, you didn't even bother to think about or
didn't even know such scale existed. If you wondered where those crap came
from, it originated from a geological-chemistry aspect.

>>You still have a lot to learn.<<

If you still want to doubt the whole thing, go ahead. Please troll my 3
year study in geochemistry. And if that isn't good enough for you, you
can write to my dad who has been in the precious metal plating industry
for over 30+ years. And I can bring more people in if you wish to know
the real truth.
""

 

[zoobyshoe]

I am not able to put the slightest mark on a nickle, quarter, or penny with my thumbnail. However,as Gokul mentioned, if a person had some abrasive grit imbeded in their nail it might give the false impression the nail was scratching the metal.

I happen to have an old silver dime, though,and it seems that by pressing very hard with my thumbnail and sliding it sideways, I was able to put a very slight mark on the face of Mercury. You might want to try this and see if you get the same results.

 

[QuantumTheory]

I am not able to put the slightest mark on a nickle, quarter, or penny with my thumbnail. However,as Gokul mentioned, if a person had some abrasive grit imbeded in their nail it might give the false impression the nail was scratching the metal.

I happen to have an old silver dime, though,and it seems that by pressing very hard with my thumbnail and sliding it sideways, I was able to put a very slight mark on the face of Mercury. You might want to try this and see if you get the same results.

I believe you.

 

[QuantumTheory]

does anyone else know?

 

[Gokul43201]

Gold's hardness is around 2.5 and copper is around 3.0. We all should know that diamond is the hardest at 10.Your fingernail
whereas has a hardness of 2.5 to 3.0 at maximum if you try really hard.

I have a feeling the hardness numbers for a fingernail (2.5 to 3.0 MOHs) are a little exaggerated, but it may be possible. They are a bit higher than the Vicker's scale numbers that I dug up for keratin. However, the clause "if you try really hard" shows that this person either doesn't understand hardness, or is being disingenuous. The hardness value is a material property, and it DOES NOT CHANGE with how much effort you apply.

Conclusion? Gold and copper CAN be scratched.

Gold - possibly. Copper - I doubt it.

Gold alloy? You should know the story. Gold alloy just got harder in between 2.5 to 3.0.

Depending on the alloying elements, the hardness can get higher than that, though it's unlikely.

Of course,a steel knife can wreck a gold coin easily - it has a hardness of 5.5 to 6. A gold alloy wouldn't be able to stand against it.

But a fingernail has way lower hardness than steel. This isn't about scratching coins with a steel knife.

If you hate to believe every single word I said, you can always do an experiment, especially the highest raised point. That will ruin your coin easily and if you are to be clever enough, you ought to researching harder

I kind of agree with this, though I have no idea what the "highest raised point" is - that's certainly not not any term I've come across in hardness testing.

 

[QuantumTheory]

I have a feeling the hardness numbers for a fingernail (2.5 to 3.0 MOHs) are a little exaggerated, but it may be possible. They are a bit higher than the Vicker's scale numbers that I dug up for keratin. However, the clause "if you try really hard" shows that this person either doesn't understand hardness, or is being disingenuous. The hardness value is a material property, and it DOES NOT CHANGE with how much effort you apply.

Gold - possibly. Copper - I doubt it.

Depending on the alloying elements, the hardness can get higher than that, though it's unlikely.

But a fingernail has way lower hardness than steel. This isn't about scratching coins with a steel knife.

I kind of agree with this, though I have no idea what the "highest raised point" is - that's certainly not not any term I've come across in hardness testing.

This was actually a converstaion started when I bought from a coin dealer who gave me a cleaned, possibly polished coin which had a black streak on it, possibly a scratch. Since cleaning and polishing coins decreases the value DRASTICALLY and RUINS the value, and the black part also ruins the value, this dealer is not recommend to buy from.

It got out of hand however.

I agree with you, I don't think this person knows what he's talking about. What he says at the end to try the highest raised point is this: Coins are struck from polished dies. When this happens, it leaves raised points on the coin called relief. Certain parts of the coin have higher relief areas than others. The highest part of the coin with the biggest relief is the highest raised point.