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Author Topic: Copper Content of Lampsacus Electrum types  (Read 1035 times)

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Offline glebe

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Copper Content of Lampsacus Electrum types
« on: October 17, 2021, 12:39:42 am »
Two of the odder coins listed in Gitler et al's XRF analysis of the early electrum coins are the two late 5th cent. types from Lampsacus (coins 44 & 45).

These types are in the style of the contemporary Kyzikene types, but the alloy compositions are rather different.

The gold contents of the Lampsacus coins are 58 and 59%, which matches the Kyzikene types, but whereas the copper percentages at Kyzikus are generally quite high, in the range of 3-5% or more, the figures for Lampsacus are 0.30 and 0.31%.

Now these figures are amazingly low, much lower than for pretty well all of the other coins listed (particularly the later types).

Except of course for our old friends the two plain types of Samos (coins 1 and 36), for which the copper figures are 0.61 and 0.35%.

What does this mean, I hear you cry.

Ross G.

Offline glebe

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Re: Copper Content of Lampsacus Electrum types
« Reply #1 on: October 17, 2021, 04:11:20 am »
Actually I tell a lie. Among the 91 Kyzicene examples there are a small number with ultra-low copper levels, namely coins 85 (0.60%), 56 (0.53%) and particularly 97 (0.19%) and 98 (0.13%). And a few more with copper levels around 1%.

Otherwise the figure is generally something like 3% or more.

Did they forget to add the extra copper?

Ross G.

Oops - should be coins 85, 86, 96 & 97.

Offline SC

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Re: Copper Content of Lampsacus Electrum types
« Reply #2 on: October 17, 2021, 09:04:44 am »
Supply chain problems 25 centuries ago....

SC
SC
(Shawn Caza, Ottawa)

Offline PtolemAE

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Re: Copper Content of Lampsacus Electrum types
« Reply #3 on: October 18, 2021, 12:45:29 pm »
Actually I tell a lie. Among the 91 Kyzicene examples there are a small number with ultra-low copper levels, namely coins 85 (0.60%), 56 (0.53%) and particularly 97 (0.19%) and 98 (0.13%). And a few more with copper levels around 1%.

Otherwise the figure is generally something like 3% or more.

Did they forget to add the extra copper?

Ross G.

Possible the difference is (trace) copper content of the silver used to dilute the gold, i.e. maybe no use of copper as a separate alloy component and no knowledge by makers of how much copper was even present. Might be helpful to know the full elemental composition from the two locations to see if content of other elements like lead, zinc, antimony, etc. correspond to differences in copper content. Could be less to it than meets the eye.

PtolemAE



Offline glebe

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Re: Copper Content of Lampsacus Electrum types
« Reply #4 on: October 18, 2021, 05:49:22 pm »
Quote from: PtolemAE on October 18, 2021, 12:45:29 pm
Actually I tell a lie. Among the 91 Kyzicene examples there are a small number with ultra-low copper levels, namely coins 85 (0.60%), 56 (0.53%) and particularly 97 (0.19%) and 98 (0.13%). And a few more with copper levels around 1%.

Otherwise the figure is generally something like 3% or more.

Did they forget to add the extra copper?

Ross G.

Possible the difference is (trace) copper content of the silver used to dilute the gold, i.e. maybe no use of copper as a separate alloy component and no knowledge by makers of how much copper was even present. Might be helpful to know the full elemental composition from the two locations to see if content of other elements like lead, zinc, antimony, etc. correspond to differences in copper content. Could be less to it than meets the eye.

PtolemAE

The XRF figures are available here:

https://www.researchgate.net/profile/Haim-Gitler/publication/338676783_XRF_Analysis_of_Several_Groups_of_Electrum_Coins/links/611ce6640c2bfa282a514671/XRF-Analysis-of-Several-Groups-of-Electrum-Coins.pdf

The figures for the trace elements for the Kyzicene coins 96 & 97 (not 97 & 98 - sorry) other than Cu are quite normal.

Also there are four other examples of this particular series (von Fritze 121) in the tables which have the usual 3% or so of Cu.

So I'm wondering whether the super low Cu figures for coins 96 & 97 might be typos. Similarly 85 & 86 (56) perhaps.

Ross G.


Offline Altamura

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Re: Copper Content of Lampsacus Electrum types
« Reply #5 on: October 19, 2021, 01:39:08 am »
... So I'm wondering whether the super low Cu figures for coins 96 & 97 might be typos. Similarly 85 & 86 (56) perhaps. ...
For each of these four coins the contents of all elements add to nearly or exactly 100%, so a typo is extremely unlikely :).

Regards

Altamura

Offline glebe

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Re: Copper Content of Lampsacus Electrum types
« Reply #6 on: October 19, 2021, 03:50:59 am »
Good point - so we're back where we started.

Ross G.

Offline Pharsalos

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Re: Copper Content of Lampsacus Electrum types
« Reply #7 on: October 19, 2021, 06:45:34 am »
I think the study shows the ancient mints were aware of the copper content, and actively manipulated this to improve the ‘gold’ appearance. As the authors note, there is a pattern to the copper . Relatively high silver coins won’t always have high copper; but where there is high copper, there is high silver.

I went through the tables of all 209 coins in the study and made some calculations.

Of the top 10 lowest copper content coins, average gold content is 63.92% and average silver content is 34.53%.

Compare that to the top 10 highest copper content coins, where average gold content is just 43.43% and average silver is 46.75%. 8 out of these 10 have more silver than gold, compared to none of the 10 in the lowest copper coins.

The copper effect is well illustrated by Kyzikos staters 95 and 96 in the study. Both have 61% gold, but 95 has 34.6% silver and 2.96% copper compared to 96 which has 37.47% silver and just .19% copper. On XRF analysis 96 is the more precious metal rich coin (and .05 grams heavier), but based on the photos anyway I’d bet the average ancient grocery shopper would prefer 95:

Offline Altamura

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Re: Copper Content of Lampsacus Electrum types
« Reply #8 on: October 19, 2021, 11:34:34 am »
Quote from: Pharsalos on October 19, 2021, 06:45:34 am
... I think the study shows the ancient mints were aware of the copper content, and actively manipulated this to improve the ‘gold’ appearance. As the authors note, there is a pattern to the copper . Relatively high silver coins won’t always have high copper; but where there is high copper, there is high silver. ...
If you have a look into Wolfgang Fischer-Bossert, "Phanes: A Die Study", also from the "White Gold" book, pp. 423–476, then you see the same tendency in table I:
https://www.academia.edu/42660629/Phanes_a_Die_Study_in_P_van_Alfen_U_Wartenberg_W_Fischer_Bossert_H_Gitler_K_Konuk_and_C_Lorber_eds_White_Gold_Studies_in_Early_Electrum_Coinage_New_York_Jerusalem_2020_pp_423_476

From the same author you find in "Electrum Coinage of the 7th Century B.C.", in O. Tekin (ed.), Second International Congress on the History of Money and Numismatics in the Mediterranean World, 5-8 Jan. 2017 Antalya. Proceedings (Istanbul 2018), pp. 15–23, on page 19 a diagramm (cited from Moesta and Franke, "Antike Metallurgie und Münzprägung", 1995) where it is roughly shown how the content of gold, silver and copper influences the color of the alloy.

Regards

Altamura

Offline glebe

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Re: Copper Content of Lampsacus Electrum types
« Reply #9 on: October 19, 2021, 05:49:48 pm »
So it seems that the occasional low Cu Kyzicenes are just that – occasional oddities, whereas at Lampsacus it appears (on the basis of just two examples admittedly) they Just didn’t add Cu.

The interesting thing about the super low Cu examples is that they give us some idea about the effectiveness of ancient refining, on the assumption that their alloy is a mix of refined gold and silver with no extra Cu.

Ross G.

 

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