Author Topic: Purity of early Islamic gold coins  (Read 2560 times)

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Offline Pellinore

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Purity of early Islamic gold coins
« on: May 08, 2015, 12:18:55 PM »
In a coin description, I read that early Islamic gold coins (before (say) 1000 AH) only consist of about 50 % pure gold. I can't believe this, but where can I find information about the purity of mediaeval gold coins?
Thanks,

Paul

Offline THCoins

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Re: Purity of early Islamic gold coins
« Reply #1 on: May 08, 2015, 10:08:11 PM »
Can't give you an answer for all medieval coins.
I do have a reference to an article by "A. Gondonneau and M.F Guerra, The circulations of precious metals in the Arab empire. Archeometry 44, 2002." This is a study which tried to answer this question by examining the gold content of Islamic gold dinars of different regions and periods. The alleged low purity of 50 % is definitely not supported by this study.

Offline Pellinore

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Re: Purity of early Islamic gold coins
« Reply #2 on: May 09, 2015, 12:18:17 AM »
This study is interesting. A. Gondonneau and M.F. Guerra trace back ancient gold to its mines through the analysis of particles from other metals. For this study, 234 dinars mainly from the Mediterranean area and the Middle East were examined from the 7th-13th century AD. It says that the Islamic gold (and silver) coins until about 750 AD were minted from older coins (Byzantine and for the silver, Sassanian), but after that (under a more decentralized government) gold from 'local' mines was used. For instance, the Egyptian dynasties used gold from Sudan mines, that was often 97-99 % pure.

As for the answer to my question, many dinars were composed from more than 95 % gold, a large majority more than 90 % and only very few under 80 % with an absolute low of 60 % for one early (AH 98) Carthage coin.

One would hope more of these technical detail studies about ancient coins will be published. The word 'Archaeometry' is music to my ears.

Paul

Offline EWC

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Re: Purity of early Islamic gold coins
« Reply #3 on: May 10, 2015, 08:40:52 AM »
In a coin description, I read that early Islamic gold coins (before (say) 1000 AH) only consist of about 50 % pure gold. I can't believe this,

Great comment Paul.  As I understand it the aim of the Arabs under 'Abd al Malik - and many others - was 100% purity, and its only matters of technical and practical competence that led to an shortfall (and maybe occasionally honesty).

Fairly easily accessible results can be got (I think) for silver from the files of the Yahoo Sasanid group - where Gordius lodged a lot of data on Sasanid and Umayyad issues.  As I recall many dirhems from Wasit came out at above 99% purity.  That was higher than was achieved by the Sasanids and the smaller Arab mints - which seems to show that the Arabs were re-refining Sasanid silver, and that - as one would expect - the big mints were more technically proficient.

On gold - in addition to Ton's data - a lot of work has been done, but its has just been ignored.  Lutz Ilisch was involved in a huge study at Tuebingen, and I think was disappointed that it received so little attention after it was published.  I looked for a copy in the UK, but I think there were only two or three copies mentioned in any libraries in the UK at all, and none that I had access rights to.  I needed the small billon section.  An acquaintance in the USA managed to get access to the Harvard copy for me.

More work has certainly been done – I recall Nick Lowick did some too. 

One of the problems behind the dissemination of these conclusions is that internet discussions on it tend to draw out a lot of people who know just a little about x-ray spectroscopy and not much about coins at all, who get on their pet soap box and start trashing the results.  Kind of like discussions of weight standards and economics rapidly degenerate to the point where talking dinosaurs are raised.  Such is life.

This is all from memory.  I can try to dig out exact references if you really need them

Offline Pellinore

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Re: Purity of early Islamic gold coins
« Reply #4 on: May 25, 2015, 07:04:54 PM »
Thanks for your extensive answer. Could you help me with the title of Lutz Ilisch's work? I couldn't find it in Worldcat, but maybe I should look elsewhere.
I found the Yahoo group though, there's a lot to read now...

Paul

Offline EWC

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Re: Purity of early Islamic gold coins
« Reply #5 on: May 26, 2015, 10:27:31 AM »
Thanks for your extensive answer. Could you help me with the title of Lutz Ilisch's work? I couldn't find it in Worldcat, but maybe I should look elsewhere.

Here is the World cat title:

Dirham und Rappenpfennig : mittelalterliche Münzprägung in Bergbauregionen / Analysenreihen
Author:    Lutz Ilisch; Sönke Lorenz; et al

Here is a comment I made a few years back

Does anyone much read this stuff anyway? Lutz got the Tuebingen project to
analyse a lot of jitals, and I was keen to get to see the results – but not
quite keen enough to lay out GBP 50 for the few relevant pages. So I did a
library search and no accessible Library in the UK had bought a copy (Not York,
Leeds, Senate House (London), nor the British Library. So I phoned the BM, and
they did not have a copy either. Cambridge did have a copy, and I arranged with
Mark Blackburn to call in as I drove past and copy it at the Fitz. But that
fell through when Mark got ill again. So I contacted an acquaintance with
access to the Harvard copy in the USA.

Offline Pellinore

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Re: Purity of early Islamic gold coins
« Reply #6 on: May 26, 2015, 01:56:14 PM »
Thanks, that helps! I saw this title alright, but didn't think it was the one you meant (because of the Rappenpfennig).

Now I see there the book consists of two volumes, being Nr. 17 and 19 of the Zeitschrift für Archäologie des Mittelalters (2003 and 2004), totaling some 400 pp. They are for sale for (together) about 120 US$, but the Royal Library (KB) in Den Haag has a set (libraries in Amsterdam and Deventer have them, too), so I will take a look in the KB one of the next weeks.

Paul

Offline Ancientnoob

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Re: Purity of early Islamic gold coins
« Reply #7 on: June 10, 2015, 02:31:28 AM »
In a coin description, I read that early Islamic gold coins (before (say) 1000 AH) only consist of about 50 % pure gold. I can't believe this, but where can I find information about the purity of mediaeval gold coins?
Thanks,

Paul

If you own one of these coins you can figure out how much the coin deviates from pure gold based on specific gravity with a margin of error. You get in the ball park.
"Everything is worth what its purchaser will pay for it."

- Publius Syrius

Offline Pellinore

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Re: Purity of early Islamic gold coins
« Reply #8 on: June 12, 2015, 09:52:19 AM »
Maybe I don't quite understand you, but for an estimate of the purity, weight isn't enough, you also need to measure the mass, and I don't know how to do that in an exact manner (dip it in a glass of water?). And if you know the density, you don't know if the gold has been mixed with copper (a bit more) or silver (a bit less), or any other metal.

I have two dinars, one Tulunid of 4,27 gr. and a Fatimid of 4,2 gr.
-- Paul