American Buffalo Gold coin dimensions?

Question

Hello there,

I have this little problem:

The American Buffalo Gold coin is said to measure 32.7 mm by 2.95 mm (according to the US mint and Wikipedia). It is also made of 24 kt Gold (.9999 purity). However, when worked out mathematically, it results that either these coins have a higher gold content than 1 troy ounce 31.1035 grams (at the given diameter and thickness / height).

Here's how I worked it out:

Volume = Pi x R x R x H

Therefore, Vol. = 3.142 x 1.635 cm x 1.635 cm x 0.295

Answer = 2.4775 cubic cm (or ML)

The density of Gold is 19.32 grams / CC;

Therefore, 2.4775 cc x 19.32 g = 47.86 grams OR 1.53873473 Troy oz. (as opposed to 1 troy ounce, as it is supposed to weigh).

So, as a bottom line: Either they use something else apart from the gold (something denser / "heavier" than gold) or their dimensions are wrong OR they're giving 1/2 ounce of gold for free (which is very unlikely)!

I will appreciate if anyone can illuminate me about this matter!

Thanks a lot,

Kramsor

Answer 1

I checked the sources you gave and checked your numbers.

It seems a very good question.

the U.S. mint site gives a locater for dealers selling the coin.

Depending on where your are located would it be practical to put this question to a dealer?

Answer 2

They are not perfect cylinders.  (You are using the height of the edge of the coin as if it were this thickness everywhere...sadly it ain't so).  So to find the volume, you must submerge then in water and find out how much liquid they displace.

Darn! And if you were right, I was going to go buy every one I could find!

Again, I don't know how else to explain it (nor do I understand why there are more answers to this)...coins are not cylinders.  They are tiny little works of art whose deminsions are not able to be listed as simple diameters and heights.  The government did not "s***w up" and put any more "pure" gold in than they said.  I agree with the fellow below...Go ahead ask a coin dealer and if they think you are right, I have a TON of gold coins I'd like to sell them by "volume".

-Fred

Answer 3

The coin doesn't have a constant width (the edges are reeded) or a constant thickness (the rim is raised), so it's not a perfect cylinder.  To get the actual volume of this coin you'd have to see how much water it displaces.

Answer 4

1) Your computations are flawless.

2) The dimensions are not the dimensions of a perfect cylinder.

Explanations :

The rim is 2.95 mm but the interior is not.

Obviously the head is higher than the background and the buffalo is also higher than the background.

PS I think you have a point.

Write to

http://www.usmint.gov/mint_programs/buff...

and

With precise instruments measure the weight and the volume of a coin.