Coins

[Rothe]

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Any coin experts/collectors want to educate me?

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I'm not a collector but have seen and handled ancient coin collections, it is a very odd feeling holding in your hand (even if gloved) something over 2,000 years old. Well at least for someone for the US. All the silver and gold roman and greek coins I've seen were small, about the size of US dimes. They certainly were not flat or perfectly round, even the ones in excellent shape.

 

[Treebore]

My experience as well, Rothe.

 

[Agback]

So, what sort of formulas would I need to use in order to figure out how thick they are?

If you have a cyclinder with a diameter of D and a thickness of h, its volume is

V = pi * h * D^2 / 4

And if it is made of a material with a density of rho its mass is

M = rho * V

= pi/4 * rho * h * D^2

To find thickness:

h = 4/pi * M/(rho * D^2)

approximately

h = 1.27 * M/(rho*D^2)

Here is a very important hint: work either in pounds and inches, or in metric. Do not work in pounds and millimetres. First, decide what sorts of pounds you mean. Troyes pounds (373 grammes)? Avoirdupoids pounds (454 g)? Tower pounds (326 g)? Then either convert your fractions of a pound into grammes or convert your millimetres into inches.

You will need to know the densities of the variious mintage metals. Here are their values in grammes per cubic millimetre. You can't convert to ounces or pounds per cubic inch until you decide which ounces and pounds you mean.

Copper: 0.008 94 g/mm^3
Silver: 0.010 50 g/mm^3
Gold: 0.019 32 g/mm^3

Platinum and lead aren't mintage metals, but their densities are

Platinum: 0.021 45 g/mm^3
Lead: 0.011 35 g/mm^3

Surprising, isnt' it? A gold-painted lead brick is much too light for anyone to mistake it for gold.

 

[Agback]

1 gp = 10 sp = 100 bp = 1000 cp. The bp is a bronze piece.

Hmm. Bronze is 90% or more copper, and 10% or less tin or arsenic. It is an easy alloy to make.

So your bp contains about 0.9 cp worth of copper, and 9.1 cp worth of tin. If 1/10 of a coin weight of tin is worth 9.1 cp, tin is worth 91 cp per coin weight, or nearly as much as gold!

No wonder your campaign moved into the Iron Age!

 

[Agback]

Any coin experts/collectors want to educate me?

Platinum was unknown in mediaeval Europe, and platinum coins have never been in circulation. It doesn't tarnish as silver does, but it is not such an attractive colour. It's price is high because of its use as a catalyst in chemical industry, not because it is treasured for making jewelry. In pre-industrial conditions it would likely not be very valuable: the first response of teh Spanish, when they discovered that platinum alloys in gold could not be detected by standard assaying techniques of their time, was to collect all the platinum they could find and drop it into the mid-Atlantic. And platinum is too hard and not ductile enough for making coins out of anyway.

The original foundation of mediaeval currency was the libra (livre or pound) of pure silver, weighing 326 grammes. This was minted as 240 denarii (deniers, dinars, pfennig, or pennies), each weighing 1.36 grammes. Denarii were small coins, about 16 mm in diameter, and yet rther too valuable to be convenient for everyday transations. People often cut them in half to make half-pennies and into quarters to make farthings.

Later, the convention was established that twelve pennies made a shilling or sou, and that twenty shillings or sous made a pound. But that was an account-keeping device, it does not imply the existence of an actual shilling coin containing 16.3 g of silver.

English coin was not debased during the mediaeval period. From the time of Offa to the time of Richard III the English penny remained pure silver and fair weight. On the Continent, however, various dynasties debased their countries' coin, to the point where the denier and pfennig became copper coins and new silver coins such as the gros (nominally fourpence) and the schilling and sous (12 pence) had to be introduced.

The English shilling, introduced in Tudor times, contained four pennyweights of silver, and was worth twelve pence, showing you that the Tudor currency was debased by 67%. The standard thus established was maintained until the twentieth century, though as the real value of silver and gold (ie. compared to wages and food prices) fell larger silver coins had to be introduced (the English florin worth 24 pence and the half-crown worth 30 pence), as well as a gold coin (the guinea, replaced in 1820-odd by the sovereign and half-sovereign)

As for a gold coin, the nearest thing to a standard was a coin weighing about 3.5 grammes, minted at Florence as a florin, at Venice as a ducat, and at Byzantium (known in western Europe as a 'bezaint' or 'bezant'). The écu was a French imitation, soon debased. The relative price of silver and gold varied, and so, therefore, did the value of a ducat in pennies. As a representative average, figure a gold as worth 15 times the price of silver, and a ducat as worth about 36-40 pence.

 

[Staffan]

Debasing is the reason Henry the VIII was nickname ‘Old Copper nose’, when on the third coinage of his money he lessen the silver content.

Stuff like this always reminds me of the book where a hero is in a foreign kingdom whose coins aren't accepted by surrounding nations. He for some reason has to hunt down a werewolf, and does the usual "melt coins to make arrowheads" thing. Eventually he encounters the werewolf, shoots it, and realizes exactly why the coinage isn't accepted elsewhere...