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Author Topic: Gold content of early Striated Electrum Types  (Read 250 times)

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Offline glebe

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Gold content of early Striated Electrum Types
« on: October 22, 2021, 03:08:51 am »
Also interesting in Gitler et al are the figures for the early striated types from (?)Miletus.
The gold content ranges from 60 to 64%, with low Cu figures.

The narrow gold range suggests that even these very early types were made from an artificial blend of refined gold and silver. Mixed in a ratio of 5/3 this would give a nominal gold content of 10/16 = 62.5%, less maybe a percent for the impurities. This would fit the data pretty well, although I would like to see more data.

On the subject of data, it’s noticeable that we don’t seem to have any alloy figures for the early types of (?)Ephesus, i/e, the unfigured types listed as Group I in Weidauer, and the early walking bees. There is clearly still much to be done.

Ross G.

Offline Kevin D

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Re: Gold content of early Striated Types
« Reply #1 on: October 22, 2021, 12:08:39 pm »
Below are my notes from the quoted sources, for early electrum 'striated' coins. I didn't clean it up, but it should be easy to pick out the analysis data. I hope this is considered 'fair use'.

Maryse Blet-Lemarquand and Frederique Duyrat  ‘Elemental Analysis of the Lydo-Milesian Electrum Coins of the Bibliotheque National de France Using LA-ICP-MS’  pages 337-378 in  ‘White Gold: Studies In Early Electrum Coinage’  (2020)
Pages 337-338, Introduction.
Pages 338-340, Provenance of the Collection of Paris.
Page 340, The Elemental Analysis of Electrum Coins.
Pages 340-348, Presentation of the LA-ICP-MS Analysis of Electrum Coins.
Pages 342-344, Appraisal of the Reproducibility.
Pages 343-344, “A Byzantine coin made of a gold-silver alloy was analyzed several times…The byzantine alloy appears to be much more homogeneous when analyzed with the LA-ICP-MS method than the early electrum coins. This can be explained by the techniques of manufacture that included several hammerings and annealings of the blank before striking, a method that homogenized the alloy. Conversely, many clues led us to think that the electrum blanks had not seen much preparation before minting: the shape of the edge is rounded; the coins are thick; dendrites that form when alloys rapidly cool were often observed in the hollows at the surface of the coins (Fig. 4); and the striking of the punch on the reverse led to the formation of numerous cracks that show holes inside the coin. In fact, holes can always be observed on the cross-sections of electrum coins whether in solid alloy or plated; they come from gas bubbles trapped in the cooling alloy. Annealing of the blanks would have more or less eliminated the dendrites and helped the alloy to deform. Hammering would have flattened the holes inside the blank. Thus the electrum alloy has not been homogenized after casting, and that explains the compositional discrepancies that can sometimes occur between different laser samplings of a same coin.15
(15) “Paszthory undertook metallographic studies on cross-sections of two Lydian coins: “This showed that the flans of [them] were cast and contain many air-bubbles, and that they were struck cold, without any annealing (Paszthory 1980: 152).”
Page 344, Table 3 fold-out, Composition obtained using LA-ICP-MS, averaged content. Striated Surface, 0.62 grams. Au%: 60.3; Ag%: 39.1; Cu%: 0.5; Bi: 224ppm; Pb: 264ppm; Pd: 7ppm; Pt: 41ppm; Pt/Pd: 6.1ppm; Sn: 21ppm.
Pages 344-348, Comparison Between Methods Performed for Analyzing Early Electrum Coins. The LA-ICP-MS method gives the most accurate results, but it is destructive. The XRF is non-destructive, but it only analyzes the surface, which is often ‘enriched’, so the gold reading can be misleadingly higher than what would be seen in the interior of the coin.
Page 345, Table 4, Comparison between XRF and LA-ICP-MS. Striated 1/12, 1.16 grams. Au%: XRF 63.8, LA 58.6; Ag%: XRF 35.5, LA 40.6; Cu%: XRF 0.74, LA 0.79.
Pages 348-356, LA-ICP-MS Results.
Page 348, “Table 5 presents the elemental composition in selected elements (gold, silver, copper, lead, palladium, and platinum) of the coins belonging to the main series that are discussed in the following pages. The coins are classified by groups based on related types.”
Page 348, Smooth and Striated Surface Coins. “The sample contains three coins with a smooth surface and six coins with striations on the surface. It was once believed that coins of both these types were among the earliest electrum coins. However, hoards testify that coins plain and/or striated surfaces and coins carrying types circulated together, which means they were issued in a relatively short span of time. Five striated coins present a very consistent composition with about 60% gold and 39% silver, while the sixth specimen appears to be a bit richer in gold (65%) and poorer in silver (34%). The concentrations of trace elements are quite consistent and rather low. The three coins with a smooth surface do not have a consistent composistion. One contains 56% gold and 42% silver, while the two others look more silvery and contain about 37% gold, 59% silver, and 4% copper. Some initial trends can be determined from our small sample; however, it would be necessary to enlarge it to answer the following questions: do the striated coins always have a fixed elemental composition, or can different compositions be distinguished that agree with the reverse punches? 34 What is the meaning of the differences among the smooth surface coins? Did several minting authorities issue smooth coins? Studies on the punches borne by the reverse of this type of coin could help to answer some of these questions.”
(34) B. Weisser, this volume, was able to distinguish different groups of striated coins based on the punches.
Pages 350-354, Table 5, LA-ICP-MS results in % or ppm for the Lydo-Milesian early electrum coins.
Page 350, Type: Striated. A trite (no image). Weight: 4.77; Au%: 60.7; Ag%: 38.5; Cu%: 0.6; Pb: 622ppm; Pd: 6ppm; Pt: 33ppm.
Pages 356-361, The Debasement of Gold. Interesting information in this section.
Pages 356-357, “Gold nearly always occurs as a gold-silver alloy that typically contains 5-20% silver; in some deposits it is essentially pure, whereas in others, the silver content may exceed 50%. We saw that the 60-40% gold range characterizes the composition of the striated surface coins and of all the animal-type coins, Lydian coins included…Copper ranges from 0.4% to about 5% and silver from 39% to 65%. The contents of these elements are most of the time higher than what could generally be found in natural gold. Thus early electrum coinage was made of an alloy that is at least partly artificial.”
Pages 361-364, The Platinum Elements. Interesting information in this section.
Page 362, “We also have to consider that [Platinum Group Element] PGE inclusions can be observed at the surface of all the electrum coins containing at least 100 ppm platinum. These hexagonal, tabular or round tiny particles (maximum measurements around 200-300 mm) have a blueish or steely gray color. They have been identified at the surface of ancient goldworks for several years. They are usually time made of an alloy of osmium, iridium and ruthenium…Meeks and Tite have found PGE inclusions in about a third of the Lydian and Ionian electrum coins, and in their sample the Lydian coins also show more inclusions than the Ionian
Page 363, Images of PGE inclusions are found on this page. “What can be deduced from the presence of PGE inclusions? They are an indication that the gold came totally or partially from placer deposits in which the gold and the PGE grains became associated as a result of fluvial transport. However, the elemental compositions of the PGE inclusions proved to be too variable to provide reliable information for gold provenance.”
Pages 364-366, The Plated Coins. Interesting information in this section.
Pages 366-368, Conclusions And Prospects.
Pages 369-374, Catalogue.
Pages 375-378, Bibliography.

Haim Gitler, et al.  ‘XRF Analysis of Several Groups of Electrum Coins’  pages 379-422 in  ‘White Gold: Studies In Early Electrum Coinage’  (2020)
Pages 379-380, Introduction.
Page 380, The Analysis.
Page 381, Group 2. Striated Type (Table 2). “The six coins in this group (nos. 2-7), which includes four different denominationsstater, ½ stater, 1/3 stater, and 1/6 stater – show a reasonable consistency in their alloys across the type and denominations, something which is not always observable in other series analyzed here. The averaged compositions for these coins are 61.9% of gold; 35.6% of silver and 0.9% of copper. These results are consistent with those obtained by Blet-Lemarquand and Duyrat (this volume), who analyzed five coins of this type and obtained averaged figures of 60.2% of gold; 39.6% of silver and 0.5% of copper.”
Pages 382 and 412, Table 2, coin number 6. A hekte. Weight: 2.4 grams, Au: 62.96%, Ag: 33.85%, Cu: 1.23%, Sn: 0.52%, Ti: 0.20%, Hg: 0.22%, Fe: 0.97%.
Pages 409-410, Conclusions.
Pages 410-411, Bibliography.
Pages 412-422, Plates.

Offline Kevin D

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Re: Gold content of early Striated Types
« Reply #2 on: October 22, 2021, 03:51:20 pm »

On the subject of data, it’s noticeable that we don’t seem to have any alloy figures for the early types of (?)Ephesus, i/e, the unfigured types listed as Group I in Weidauer, and the early walking bees.

Ross G.

Regarding the 'walking bees', I've also seen this type referred to as a bee from the back, with wings at each side. In the latter description, there is so much variation in the 'wings' that they were not making sense as wings to me. Indeed, this type might not even be meant to represent a bee, but a bee does seem to be a likely candidate. In looking at images of this type, they often seem to depict only the thorax and abdomen of the 'bee'. Sometimes a 'head' appears to be intended, but often there is nothing more than what is seen to either side of the 'bee from the back', which looks to me like an irregular pattern, rather than wings.
I offer for consideration that what is intended with this type is a bee on a flower. The wings, being transparent, are not depicted, but rather what is seen surrounding the thorax and abdomen are the elements of the flower. The head of the bee is also not depicted, as it is arched forward and into the flower. This is what I see when I look at bees in my yard on flowers, collecting pollen.

Offline glebe

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Re: Gold content of early Striated Electrum Types
« Reply #3 on: October 22, 2021, 05:59:55 pm »
Yes I also had trouble with the walking bees (Weidauer 29-32), but I think it's (fairly) clear that these crude early types show the bee from the side, not the top.

On the image shown above the head is at the top, almost off the flan, with the legs to the left and the wings folded down the back on the right.

Another slightly clearer example is shown below, with the bee walking left.

That said, the obvious question is why would you depict a bee from this odd angle?

Ross G.

Offline glebe

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Re: Gold content of early Striated Electrum Types
« Reply #4 on: October 22, 2021, 09:17:44 pm »
<<Page 348, Smooth and Striated Surface Coins. “The sample contains three coins with a smooth surface and six coins with striations on the surface. It was once believed that coins of both these types were among the earliest electrum coins. However, hoards testify that coins plain and/or striated surfaces and coins carrying types circulated together, which means they were issued in a relatively short span of time. Five striated coins present a very consistent composition with about 60% gold and 39% silver, while the sixth specimen appears to be a bit richer in gold (65%) and poorer in silver (34%). The concentrations of trace elements are quite consistent and rather low. The three coins with a smooth surface do not have a consistent composistion. One contains 56% gold and 42% silver, while the two others look more silvery and contain about 37% gold, 59% silver, and 4% copper. Some initial trends can be determined from our small sample; however, it would be necessary to enlarge it to answer the following questions: do the striated coins always have a fixed elemental composition, or can different compositions be distinguished that agree with the reverse punches? 34 What is the meaning of the differences among the smooth surface coins? Did several minting authorities issue smooth coins? Studies on the punches borne by the reverse of this type of coin could help to answer some of these questions.”>>

The "smooth" types are interesting ones here - one could be Weidauer Series I, but the two silvery types I don't recognise. Unless perhaps they are Linzalone's "Ram from above" type (Linz. 1110, 1012 or similar) where the obverse design is often worn off (these have a variety of fancy geometric punches as opposed to the rough punches of Weidauer Series I).

Ross G.

Offline Kevin D

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Re: Gold content of early Striated Electrum Types
« Reply #5 on: October 22, 2021, 11:31:32 pm »
Here is an image of the obverse of another ‘bee’ trite. I don’t see a head, or that one was intended. I don’t see anything I would describe as legs or wings. On these coins, in the area where a head would be located, I see only the same iregular pattern as that seen on each side of the thorax and abdomen.

HA is describing the bee on these coins as being 'seen from above' (i.e. from the back). I know Joe Linzalone has described them as showing a 'bee walking left'. Others describe only a 'primitive bee'.

Offline glebe

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Re: Gold content of early Striated Electrum Types
« Reply #6 on: October 23, 2021, 01:55:50 am »
Here is an image of the obverse of another ‘bee’ trite. I don’t see a head, or that one was intended. I don’t see anything I would describe as legs or wings. On these coins, in the area where a head would be located, I see only the same iregular pattern as that seen on each side of the thorax and abdomen.

HA is describing the bee on these coins as being 'seen from above' (i.e. from the back). I know Joe Linzalone has described them as showing a 'bee walking left'. Others describe only a 'primitive bee'.

Well if there's a thorax and abdomen there's gotta be a head, and in fact you can see a bit of it at the bottom.

Actually I suspect that the bee was actually meant to be shown on a striated background, along the lines of the various other early types (Linzalone p.176ff). This could be why Weidauer made the bees Series V, following the striated goat and cock types Series III and IV.

For another example see below, but anyway whatever the bee is doing it would be very interesting to know the alloy composition.

Ross G.

Offline Kevin D

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Re: Gold content of early Striated Electrum Types
« Reply #7 on: October 23, 2021, 01:36:26 pm »
Your suggestion that these coins might show a striated background does make sense to me. This might well be the case. The bees seem to me to be depicted with the head mostly or totaly out of view, as they often appear when seen from above (i.e. the back) when on a flower (head arched into the flower and out of view).

Whether on a flower or in that view but on a striated field, when thought of like this these coins begin to look less crude or 'primitive' than they are often thought to be.

Agree it would be good to know the alloy composition.

From Dane Kurth's translation of Weidauer:

Dane Kurth Translation  (2009)
Liselotte Weidauer  ‘Problems of Early Electrum Coinage’  (1975)
Page 17 and Plate 4. Milesian Standard. Group V. Bee. Coin numbers 29-32, Trites struck on the Milesian weight standard. O: Bee left surrounded by wedge-shape punches of different thicknesses. Rough die work. Bee's body only as a schematic rendition. R: Two incuse squares side by side. The corner of one of the punches was broken off.

[I believe that in fact the reverse is a single oblong incuse punch]




Offline Kevin D

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Re: Gold content of early Striated Electrum Types
« Reply #8 on: October 23, 2021, 03:55:47 pm »
<<Page 348, Smooth and Striated Surface Coins. “...Some initial trends can be determined from our small sample; however, it would be necessary to enlarge it to answer the following questions: do the striated coins always have a fixed elemental composition, or can different compositions be distinguished that agree with the reverse punches?...”>>

The "smooth" types are interesting ones here - one could be Weidauer Series I, but the two silvery types I don't recognise. Unless perhaps they are Linzalone's "Ram from above" type (Linz. 1110, 1012 or similar) where the obverse design is often worn off (these have a variety of fancy geometric punches as opposed to the rough punches of Weidauer Series I).

Ross G.

Plate images for the Blet-Lemarquand and Duyrat article would have been nice.

I believe I have seen striated coins which show a considerable variation of alloy from the norm (if there is a norm), some looking much more "silvery"; but trying to judge an alloy from photos can be misleading.


 

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