Author Topic: What are billon coins?  (Read 1943 times)

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Offline Learningcoins

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What are billon coins?
« on: June 12, 2015, 10:52:20 AM »
I was trying to learn a little bit about coins and while browsing online I often see coins are described as Bullion coins. What are these coins? Are they original or later made?

Example:

http://www.ebay.in/itm/Delhi-Sultan-Alaudin-Khilji-Bullion-Coins-Lot-of-3-pcs-/151711141321?pt=LH_DefaultDomain_203&hash=item2352b04dc9

Offline capnbirdseye

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Re: What are billon coins?
« Reply #1 on: June 12, 2015, 12:53:11 PM »
It's not bullion it's Billon which is an alloy of  silver & copper, some coins appear more silvery than others & some do look like silver when cleaned
Vic

Offline THCoins

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Re: What are billon coins?
« Reply #2 on: June 12, 2015, 01:50:52 PM »
The term bullion is used improperly in the link you give, as Vic states that's billon. But bullion is a term used for a certain weight of precious metal in the shape of a coin or a bar. In general bullion coins are not meant for circulation and have no real numismatic value. These are usually bought as a means of investment in gold or silver.

Offline Learningcoins

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Re: What are billon coins?
« Reply #3 on: June 12, 2015, 06:53:55 PM »
Thanks a lot Vic and THcoins. Now this makes sense :)

Offline Alan71

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Re: What are billon coins?
« Reply #4 on: June 13, 2015, 10:13:55 AM »
Bullion coins always have a ridiculously low face value for the amount of silver or gold in them.  Many countries do them but I'm more familiar with the UK ones.  The gold bullion coin (the Britannia) is one ounce of fine gold with a face value of £100, but in reality worth considerably more than that.  The gold sovereign is even more ridiculous, with a face value of £1 (although this isn't stated on the actual coin).  The silver version of the Britannia has an ounce of fine silver and a face value of £2, but sells for around £20 currently.

The Royal Mint has in more recent years started to sell silver £20 coins at face value.  What people probably don't realise is that there is less than £20 of silver in them, so they're not an investment.  The much larger and heavier (and therefore more silver) Britannias sell for a similar price but their lower face value means people don't realise they are much better value and more of an investment.

Offline Gusev

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Re: What are billon coins?
« Reply #5 on: September 25, 2015, 08:09:17 AM »
I agree with Vic.
On Ebay auction has such a description: "      Debased Billon Silver Coin    ".

Vic explained everything correctly.
This is consistent with the wording Albert R. Frey:

"Billon.
A base metal usually obtained by mixing silver and copper.
The designation is now generally applied to any coin ostensibly called silver, but containing in reality more than fifty per cent of copper. If the proportion of copper is more than seventy-five per cent, the composition is called black billon. Lastly, if the coin is of copper, and is only thinly washed with silver, it is called white copper."
« Last Edit: September 25, 2015, 10:48:04 AM by Gusev »
"Those at the top of the mountain didn't fall there."- Marcus Washling.

Offline Gusev

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Re: What are billon coins?
« Reply #6 on: September 25, 2015, 10:55:53 AM »
Albert R. Frey:

"Bullion.
The original meaning of the word appears to have been a mint or assay office, but the writers of the sixteenth century sometimes refer to it as a place of exchange.

The Termes de la Ley, 1641 (p. 43), states that "Bullion ... is the place where gold is tryed, "and Blount, in his ' 
Law Dictioiiarie, 1679, has: "Bullion . . signifies sometimes the Kings Exchange, or ... [35]
"Those at the top of the mountain didn't fall there."- Marcus Washling.

Offline EWC

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Re: What are billon coins?
« Reply #7 on: September 25, 2015, 11:43:17 AM »

"Billon.
A base metal usually obtained by mixing silver and copper.
The designation is now generally applied to any coin ostensibly called silver, but containing in reality more than fifty per cent of copper. If the proportion of copper is more than seventy-five per cent, the composition is called black billon.

Broadly agree - but am not sure that or any other convention is widely used.  I seem to find the point at which blanching AR+AE billon to whiteness is suprisingly low - 9% silver will blanch to near silver appearance - at 8% it starts to get difficult

Offline Gusev

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Re: What are billon coins?
« Reply #8 on: September 25, 2015, 12:02:21 PM »
In Bhutan in the late 18th and early 19th century minted coins with very low silver content.

In the photo (Gordian):
Bhutan, Deb Rupee, KM#3.4, B 03.35 bh, 1790-1840

Metal composition of the coin is: Ag 4.86, Cu 88.80, Zn 6.03, Fe 0.14, Au,Sn,As,Sb,Bi,Hg,Cd,Pb,Co,Ni all are under detection or error limits, Sum 99.83%, microprobe data in scanning mode on surface 80x70 mkm. The alloy is binary - groundmass of composition Ag 4.69, Cu 89.27, Zn 5.76, Ni 0.20, Sum 99.92% contains rare inclusions of silver, microprobe point data. So we have here very unusual silver bronze - zincian, tinless and leadless with Ag<Zn.
Composition of outer silver layer is: Ag 63.11, Cu 35.69, Zn 0.34, Pb 0.83, Au,Sn,As,Sb,Bi,Hg,Cd,Fe,Co,Ni all are under detection or error limits, Sum 99.97%, microprobe data in scanning mode on surface 80x60 mkm.

"Those at the top of the mountain didn't fall there."- Marcus Washling.

Offline EWC

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Re: What are billon coins?
« Reply #9 on: September 25, 2015, 12:49:23 PM »
Thanks yes.  I was thinking about medieval coins, where things might be a bit simpler - but of course that is not certain.

My guide coins are the dugani of Delhi under Balban and Alauddin khalji.  I experimented with 10% sulphiric acid and its pretty easy to blanch Balbans but more tricky to blanch Aluaddins.  Of course this is a crude way to replicate medieval processes - but the results make sense.  The mint master for Alauddin, Thakkura Pheru, is well know to be highly competent, and he cranked down the silver from 9% to 8% - that is the basis of my suggestion.

Its obvious a lot of even baser Afghan coins around 1200 were whitened - but I am not sure it was by blanching.  Looks to me like they might have concocted some sort of chemical or electochemical process (?), but I have no way to test that.

Once you start asking questions about arsenic and tin and so on too it just gets so complicated!  I had a bunch of Alexandria tets once that hardly seemed to be metal at all.

A bunch of rare post mauryan pmc's came up a few years back that looked exactly like silver after coming out of weak formic acid.  But a week later they went a sort of brown pewter colour.  Those ancient Indians knew a lot more than me about metals.........
« Last Edit: September 25, 2015, 02:35:52 PM by EWC »