Friday, July 26, 2019

Tinplate: An Inquiry for a Vacation Week

I should have taken a landscape portrait,
but it was before breakfast. 

Five weeks ago I went to visit my sister's family in Kamloops, and the familiar landscape of the Okanagan-Shushwap inspired me to respond to a reposting at Brad Delong's joint of some material from Pamela Crone's batshit  "Hagarism" controversy.

I can't say that the sources of ancient tin  have the same personal resonance for me, but the subject did come up over at Delong's, and I do feel that I have to issue a defence and expansion. I do not, personally, have strong opinions about where the ancients got their tin, but scholars I respect have arguments that are not getting their due. And given that the conversation is at an economical history blog, the fact that Niall Sharples ties tin to a "general glut" argument is germane, and ought to earn him some attention. 

It won't, of course, because he wrote a scholarly monograph about Social Relations in Later Prehistory and not some attention grabbing work of debatable generalisation, but all you can do is put it out there and hope it gets some attention.    

As you can see, a solid chunk of cassiterite is conspicuous and valuable in
its own right. By CarlesMillan - Own work, CC BY-SA 3.0,
The core problem is, and remains the same. When we talk about ancient tin, we either start with Herodotus telling us about the remote and exotic "Tin Isles," or we fall back on the lack of ancient archaeological evidence for the exploitation of a specific resource. Throw in the reference to the tin of Tarshish in Ezekiel, and you've pretty much rounded out the problem. What Herodotus is telling us about these isles of tin isn't easy to parse, Tarshish is a place out of poetry, and it really is hard to say that a given cassiterite deposit was  worked in antiquity. There you go. 
The reason that we're worrying about this is that tin is a relatively rare mineral, well-known to exist in large quantities only in a limited number of areas around the world. None of these are particularly close to the Middle East, where evidently deliberately-alloyed tin bronze pieces appear from around 3000BC. Given our unslaked interest in the period, there is a huge temptation to trace early tin-trading routes on this enigmatic map. For is it not already criss-crossed with purported language-migrations that have had no little effect on us in themselves? This imagined map 

Conan's Hyboria even takes its name from the same bit of Herodotus.
has already played its part in bringing us world wars and genocides, and if that is not enough to slake our desire to freight plain geography with our arrows of fevered desire, what is? Muhly delivers a series of authoritative statements from the geological literature that combine to support his thesis, which is that we can draw an arrow from the Cornish/Breton tin province to the Bronze Age Middle East. 

I'm no geologist, but I do know enough about this "science" thing that I am aware that it is not a good idea to let an argument rest on scientific literature that appears in your footnotes with a (1963) at the end. A decent literature review is perhaps a bit of an ask in a blog post, but I can cut and paste from Wikipedia with the best of them:
Most sources of cassiterite today are found in alluvial or placer deposits containing the resistant weathered grains. The best sources of primary cassiterite are found in the tin mines of Bolivia, where it is found in hydrothermal veins. Rwanda has a nascent cassiterite mining industry. Fighting over cassiterite deposits (particularly in Walikale) is a major cause of the conflict waged in eastern parts of the Democratic Republic of the Congo.[6][7] This has led to cassiterite being considered a conflict mineral.Cassiterite is a widespread minor constituent of igneous rocks. The Bolivian veins and the old exhausted workings of CornwallEngland, are concentrated in high temperature quartz veins and pegmatites associated with granitic intrusives. The veins commonly contain tourmalinetopazfluoriteapatitewolframitemolybdenite, and arsenopyrite. The mineral occurs extensively in Cornwall as surface deposits on Bodmin Moor, for example, where there are extensive traces of an hydraulic mining method known as streaming. The current major tin production comes from placer or alluvial deposits in MalaysiaThailandIndonesia, the Maakhir region of Somalia, and RussiaHydraulic mining methods are used to concentrate mined ore, a process which relies on the high specific gravity of the SnO2 ore, of about 7.0.

Given the difficulties that arise when a historian and an archaeologist pit geological authorities against each other, it might be best to take a careful look at what the authorities are trying to tell us. (Which, of course, privileges the historian's text-based analysis over the archaeologist's science. Yes, I'm cheating.) In 2016, the ITRI, an industry trade group, estimated a total global potential supply of tin of 11.7 megatons of tin [pdf],  and defined the biggest threat to the industry as "tin criticality." If you are thinking that that is a measure of the shortage of tin, however, you would be wrong. "Tin criticality" is when consumers respond to spikes in the price of tin by substituting other metals, notably the essentially inexhaustible iron and aluminum. Once an industry has switched over, it is not likely to switch back. ITRI's goal is to preventing these substitution effects by managing price swings by managing supply. This is not easy when some of the largest global tin resources aren't being worked at all due to the perceived lack of return. Canada, for example, has almost twice as much in tin "resources" (as distinct from "reserves") as Bolivia, but exactly zero tin is mined in Canada. And, just to complicate things, there is also a specific cassiterite mining industry exclusive of tin, because the mineral is used to make metallic glazes for pottery, a fascinating bit of physical chemistry requiring, as usual, substantial amounts of caustic soda. 

"Near" the Hamrin Mountains. Mass graves and ISIS dead enders.
Cassiterite provinces are actually not that uncommon, and can be quite large. The ore is heavy and unreactive, so as erosion opens up veins in the granite, placer deposits of cassiterite form, much as with copper and gold, and, in much smaller quantities, native silver. Placer deposits in Southeast Asia and Cornwall are either now, or in the past, the most productive in the world. The majority, however, are quite uneconomical to work, which puts us in a very difficult position. There is every reason to think that an Early Bronze Age prospector might pick up a large chunk of cassiterite from a placer. Once it is removed, we have no evidence that it existed at all! Since 1989, Turkish archaeologist K. A. Yener has promoted his excavations at Kestel, in Turkey's Taurus mountains. Dating the mining there to the Early Bronze Age, Yener has proposed the mine as the source of the earliest Middle Eastern bronze --the free hit, as it were, that addicted the world. These days, however, enthusiasts for Kestel have to jostle with proponents of Sardinia and Tuscany, where the mines at Mount Valerio was exploited during the WWII blockade, and probably since the Iron Age --for tin glaze, if not tin. 

Not content to leave these archaeological industries of knowledge to themselves, Iraqi workers have of late been championing the Deh Hossein mine, just across the Hamrin Mountains in Iran. This is one of the few lines of inquiry where archaeometallurgy has been mustered in full force. Having sat at the feet of Bert Hall, the profession's modern expert on bronze casting, I'm not sure how far the average historian or archaeologist understands how hard it is to assay the tin content of a bronze piece, much less trace its origins from the isotopic footprint. (Needless to say, that last will be a futile task taken altogether if tin sources turn out to be dispersed and oppportunistic.) The Deh Hossein mine, it is argued, was the source of a mixed copper-arsenic-tin ore that produced a natural alloy with uncontrolled constituents. Mulhy was arguing with this claim back in the 1980s, but the proponents of Deh Hossein have not given up, and have even advanced their saps to the Herodotean ditch by proposing that "cassiterite" comes from "the country of the Kassites," make of that what you will

However, all of these industries have to cope with the existence of a significant tin-tungsten deposit in the Eastern Desert of Egypt, discovered in 1940 at the site of several historic mines traditionally worked for beryl, topaz and tourmaline. An extension of the Bronze Age gemstone working to produce cassiterite for similar use, extending to the smelting of tin, is not inconceivable. To put to rest this existential threat to the arrows of imagination, it is necessary to point to the absence of evidence for early working. Which, fair enough. However, there are substantial placer deposits in the Eastern Desert of Egypt along the wadis leading to the Red Sea. The Egyptian Mineral Resources Authority has targeted these for gold mining [pdf], working from the foundations laid as early as the Bronze Age.  

By Anagoria - Own work, CC BY 3.0
At this point it will be clear that the arrows of imagination are not to be sustained without much special pleading. Of all these arguments, the most compelling is the rather obvious one that there is evidence for early tin mining in Cornwall. And why would people be mining tin, if not to use it? The Nebra Sky Disc has been metallurgically sourced to Cornwall, from whence both its gold and tin, some time before a proposed fabrication in about 1600BC. This, however, like the fabled jadeite axes of an earlier era, demonstrates the long distance hand-to-hand transmission of prestigious objects (in this case, large hunks of precious and semi-precious ores) while falling short of demonstrating the long distance trade that would bring tons of tin all the way from the Tin Isles of Cornwall and Brittany to the Middle East. 

This is the point where we need another angle. Sharples writes in his conclusion (and I have quoted before): 

"It is a little easier to to explain how catastrophic the end of the Bronze Age was, given the collapse of the financial markets that devastated national economies in 2008. In the Bronze Age, bronze was as important as money is today; it connected people and created a system whereby other people relied on others to provided materials that were not locally available, animals when they were needed for consumption and sexual partners necessary for the continuity of human communities. In times of crisis, the credit built up through the long-term exchange of gifts would enable people to acquire the essentials to rebuild their lives. It also provided a way of classifying and contrasting people and communities by status and identity. The complex system of exchange relationships, and indebtedness, which had been operating for over 1,000 years, was completely undermined and abandoned at the end of the Bronze Age." (Sharples, 312--13.)
This does a little less than justice to the scope of Sharples' argument. One of his most interesting points is that the confining and ubiquitous jewelry of the Bronze Age wasn't just status-defining. It fixed the body in life and death and reified the social order as cosmological. That is, the social order of the Bronze Age was defined as inherent to the world-as-such. Broaches, torques and gorgets confine and constrain the body and the social role at once. Think here of garments like the toga, which are designed to limit the amount of work (and perhaps more importantly, social violence?) a Roman aristocrat can do. 

Here we have a sketch of the ideological overthrow of the Age of Bronze at the Late Bronze Age collapse which is not terribly important for this discussion, but which leads to another of Sharples' points, which is. Sharples sees Bronze Age societies, at least at the periphery, as being gift-exchange "economies." Trade is not economic. It is socially embedded, and works to create status hierarchies through gifts that signify long distance relationships, rather than through exchanges that maximise wealth through comparative advantage. 

We can put meat on these bones with a nice, synoptic review of current developments in Cornish archaeology. Now, if only someone  has posted something like that to Why, thank you, Andrew M. Jones and Henrietta Quinnell. (Speaking of archaeology, this fossil completely missed the memo about "Henrietta" coming back. You have a cool name, Ms./Doctor Quinnell.) 

Take it away, Jones and Quinnell:

i) Cornwall's Mesolithic is ill-defined, which means that you're not going to be able to argue for or against the main explanations of the British Neolithic from Cornish evidence. Migration or acculturation? Your guess is as good as anyone else's! The Neolithic is defined by the tor sites on commanding positions spread throughout the county:

These appear to be cult sites rather than settlements, which remain elusive. Chambered tombs and locally-produced greenstone axes are common. Cereal depositions and animal bone accumulations are also uncommon. The former can be used to argue against an agricultural economy. The latter is hard to explain except by resort to a low population. 

ii) Cornwall's Middle Neolithic has been seen as one of declining population, but maybe there was just a decline in monument production. Either way, the implicit claim, that Cornwall was a bit of a backwater, in spite of being between France and Ireland, is still there. The Late Neolithic is the key period for henge construction in the rest of the country, and so much for Mycenaeans or Minoans building Stonehenge. The dating for Cornwall is not secure, but seems later, so we can salvage the foreign influence if we like, but at the cost of making Cornwall into a backwater again, distinctly behind the times of even nearby Wessex. 

Exception, not the rule: The Rillaton Cup.
By Fæ - Own work, CC BY-SA 3.0,
iii) The Early Bronze Age used to be a continuation of this story, inasmuch as the Beaker People (whoever they were) were not well attested in Cornwall. Some sites have now been found, so we know that they weren't avoiding the peninsula. What has not been found is an association with metalwork. The one place we see some energy on the periphery is in monument building. Some 3500 barrows and cairns of distinctly Bronze Age style have been recorded in Cornwall.  Clearly, social standing had come to be very, very important to the Cornish between 2400 and 1500BC, and it was expressed in many ways. There is a limit to how distinct one cairn/barrow can be from another, but the ways in which human remains are associated with them is much more varied: From cremations to burials, from token relics to mass burials, the ancestral cult associated with the Early Bronze Age monuments of Cornwall allowed significant variation in expression that is not seen in artifact depositions. The absence of obviously imported goods, the Pelynt Dagger aside, is an argument against an extensive trade in tin. 

iv) The Middle Bronze Age sees the craze for monument building coming to a crashing end. On the other hand, we finally have evidence for streambed tin mining. From this point, whatever and to whatever extent the Cornish were symbolically gift-exchanging, one thing that they were gift-exchanging was tin. The period sees increasingly dense settlement, in round houses, interestingly enough. (Sharples argues that the appearance of the roundhouse in Early Iron Age Wessex is part of the general reaction against Bronze Age ideology. In Wessex, it would seem to be a self-conscious attempt to go back to ancestral ways; which would make out Cornish Bronze Age populations to be reactionaries or country cousins. Nevertheless, any temptation to look backwards was not allowed to stand in the way of an apparent extension of cereal production and the establishment of field systems. 

v) Substantial changes in building styles and land use patterns are argued for the Cornish Late Bronze Age, circa 1100BC. Whether these stand against continuing excavation and more carbon datings is uncertain, but at least for the moment we have the ideological fact of the rejection of the post-ring roundhouse and the abandonment in the same period of the local, Trevisker Ware ceramics tradition which has lasted through the whole Bronze Age. Along with numerous hoards, Cornwall looks to be experiencing the Late Bronze Age Collapse early. 

In conclusion, Jones and Quinnell point out that evidence for Bronze Age Cornish building and metalwork remain sparse and elusive. While this may change, it is this context that leads Sharples to argue for a gift exchange economy. If Cornwall really were a high-pressure source of tin, pouring enough raw material into European-wide exchange networks to push tons of metal into the Middle East, we would expect to see evidence of people, social activity, metal production and trade goods in Cornwall that we simply do not. 

Might this change in the future? It certainly could! But the conclusion for the moment is that the argument for long-distance trade exchanges of tin in the Bronze Age is driven by a desire for evidence that deepens and strengthens hypotheses about population movements and language change. Only the fact that there is tin in Cornwall (and Brittany) currently stands independent of theories that allow us to propose genocidal Yamana genociding bronze producers, Minoan henge builders and Mycenaen civilisation-overthrowers. 

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