Specific Gravity of US Gold Coins

1630Boston

Some handy info if you want to calculate the specific gravity of an alloy coin
from the NNP
.

more here - https://nnp.wustl.edu/library/book/527516?page=25

1630Boston

I made a spread sheet to do the calcs
.
.

ricko

@1630Boston ... Thanks for the article and the spread sheet information. Cheers, RickO

CaptHenway

I knew Col. Kriz when I was working for ANACS. Let’s just say that we politely disagreed on a few things.

LanceNewmanOCC

@CaptHenway said:
I knew Col. Kriz when I was working for ANACS. Let’s just say that we politely disagreed on a few things.

.
it can be annoying to have an antagonist but sometimes, a little fun.

the important question is, "is there anything important that was disagreed upon with the info provided here?"

CaptHenway

Well, when you alloy silver and copper the proportional calculations work.
When you alloy gold and copper, they do not. There is something about the gold atoms that react to alloying differently.

He gives a theoretical calculation for the s.g. of 90% gold, 10% copper as 17.317. The coin world almanac charts on U.s. coin specifications give it at 17.16. THat almanac figure was derived from numerous actual s.g. tests. When I did s.g.'s on U.S. 90% gold I considered anything from 17.14 to 17.16 to be dead on.

1630Boston

@CaptHenway said:
Well, when you alloy silver and copper the proportional calculations work.
When you alloy gold and copper, they do not. There is something about the gold atoms that react to alloying differently.

He gives a theoretical calculation for the s.g. of 90% gold, 10% copper as 17.317. The coin world almanac charts on U.s. coin specifications give it at 17.16. THat almanac figure was derived from numerous actual s.g. tests. When I did s.g.'s on U.S. 90% gold I considered anything from 17.14 to 17.16 to be dead on.

I don't remember where, but I do recall reading of what you speak of above about gold and copper.

MetroD

@CaptHenway said:
Well, when you alloy silver and copper the proportional calculations work.
When you alloy gold and copper, they do not. There is something about the gold atoms that react to alloying differently.

He gives a theoretical calculation for the s.g. of 90% gold, 10% copper as 17.317. The coin world almanac charts on U.s. coin specifications give it at 17.16. THat almanac figure was derived from numerous actual s.g. tests. When I did s.g.'s on U.S. 90% gold I considered anything from 17.14 to 17.16 to be dead on.

Interesting.

Thanks for sharing this information.

FWIW, I found this to be insightful.