I also have this file saved on my hard drive, which I always found to be interesting:
HOW MUCH DOES A COIN WHEIGH?
(Source unknown)
A coin weighs 1.6 ounces avoirdupois or 1/10 pound American in official AD&D rules. This is, of course, just plain stupid.
I just got a catalogue of ancient and medieval coins ($95.00 to $2,000 plus per coin, if you're interested) and let me tell you something:
Great honking enormous coins like presented in AD&D were not at all common.
Okay, we already know that the standard unit of English currency was the penny or denier during the middle ages (penny=denier). The prototype ideal English penny was minted under William the Conquerer (some scholars may disagree with this). It was a coin that was two centimeters in diameter and made of high grade silver. It weighed, surprise, surprise, one pennyweight. How much was a pennyweight? It was legally defined as a weight equal to 1/240th a pound.
Thus, an English penny theoretically weighed 1/240th a pound. How much was a silver penny worth? Well, according to some sources I've read, you could buy what AD&D erroneously calls a "longsword" for around 20 to 40 pennies, depending on the century.
Okay, so for the sake of simplicity, we have a silver coin weighing 1/240th a pound (that's about 0.0667 common US ounces [avoir.] or 1.89 grams for our European readers). Around 20 to 40 of these silver coins could buy a "longsword".
Other common monetary units:
Unit Value
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Groat 2 pennies ("tuppence")
Shilling 12 pence
Sovereign Variable, depending on gold content.
Pound 240 pence--no pound coins were minted in medieval times.
Gold tends to value 10 to 50 times silver per weight depending upon market pressures.
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me again... gold tends to weigh more, which this author doesn't really cover.
According to
Online conversion 1 pound equals 453.59237 grams.
And, according to another site I found, a nickel weighs approximately 5 grams.
That would give us a 90 nickels to 1 pound ratio. More or less.
If we assume that gold nickel would weigh more than a standard nickel, a 50 gold nickels to 1 pound ratio wouldn't be out of the question.