Dear Luke,
Unlikely that you will find cupels at this site, which you describe as a
refuse pit. These litharge rolls form from large-scale cupellation on
hearths, of at least twenty or more cm diameter. Cupels are much later small
vessels, of just a few cm diameter and free-standing to be placed in a
furnace. You COULD find Cupellation Hearth Material, heavy white-yellowish
calcareous material soaked with around 60 wt% PbO.
But remember that the pure litharge may well have travelled long distance
(there are examples of it on shipwrecks), and in its clean form for
non-metallurgical purposes = as medical material or even pigment. Trade in
its original roll form is saver for he buyer than as a ready-made pigment
powder or medical paste, since the rolls are less easily adulterated /
diluted with cheaper filler...
Let us know please if the XRD shows anything not consitent with the various
independent visual identifications offered on this list, all of which agree
it is pure litharge. (Thus, you should find various lead oxides and
carbonates, depending on corrosion state of your sample.)
Thilo
----- Original Message -----
From: "Luke Howarth" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, July 15, 2010 1:43 PM
Subject: Re: Mystery Object
Thanks you all very much that helps a lot!
I should be getting some analysis done in a few months (sept / Oct)
which might be interesting and I can pass on the data if anyones
interested? Just email me, however it won't be until ~Oct (and it's
only XRD...).
Your comments are really quite interesting, particularly as we don't
have much evidence of metalworking of any kind on site - a few
fragments of Fe rich slags, no cuppels (though I'm going to double
check this again). I think the nearest source of argentiferous lead
(that I'm aware of) is North of Montpellier around Mount Lozere (which
would be around +100 km away) though we are just next to the coast of
course...
thanks again
L
[log in to unmask]
On 15 July 2010 14:06, Erica Hanning <[log in to unmask]> wrote:
> I showed the fotos to Frau Körlin (Deutsches Bergbau-Museum Bochum), who
> found such tubes when excavating a Roman lead mine in Lüderich (Bergischen
> Land), and when the object is actually lead, then it is probably refuse
> from extracting silver. The silver-bearing lead is melted in a crucible in
> an oxidizing atmosphere. A lead oxide is formed on the surface of the
> molten
> metal where it is then drawn off by dipping (iron) rods into the bath,
> onto
> which the lead oxide adheres - thus creating such tubes. The process is
> repeated until all of the lead is oxidized only the silver is left in the
> bottom of the crucible.
> Frau Körlin also mentioned that similiar tubes were also found at an
> excavation of a Villa in Rheinland Pfalz (Villa am Silberberg, Ahrweiler :
> http://www.bad-neuenahr-ahrweiler.de/bildung_kultur_freizeit/museen/museum_roemervilla/index.html).
> A description of the finds from Lüderich can be found in :
> Körlin, Gabriele, (2002): Die Römer auf dem Lüderich - Grabungen 2000-2002
> .
> in "Bergbau im Bergischen Land" Beispiele von Bergbauspuren zwischen Sülz
> und Wahnbach". Schriftenreihe des Geschichtsvereins Rösrath E.V. Band 32,
> 2002
> A picture of one of the lead tubes from Lüderich can be found in
> Archäologie im Rheinland 1997, p91, though is interpreted there as a lead
> weight (Bleisenker)
>
>> Date: Thu, 15 Jul 2010 12:03:55 +0100
>> From: [log in to unmask]
>> Subject: Mystery Object
>> To: [log in to unmask]
>>
>> Dear List,
>>
>>
>> While working on a site in the south of France, not far from the coast we
>> recovered a "mystery" object in a pit / "large posthole" containing an
>> assortment of archaeological debris, including a large quantity of animal
>> bone and ceramic. The feature is thought to be Antique and is not far
>> from a
>> small kiln (though this is full of spoiled ceramics). On the site we also
>> have large structural features primarily a temple and several ritual
>> deposits of metal artefacts. The site is situated on the interface
>> between a
>> butte and a floodplain which gives on to the sea just a couple of
>> kilometers
>> to the south.
>>
>> I've discussed with a local geologist just to verify if it's not some
>> kind
>> of local geological oddity, and through the course of our discussion we
>> did
>> come to the conclusions that is is probably the accidental product from a
>> metallurgical process (the geolgist in question has worked on several
>> mines
>> and I have a modest knowledge of metallurgy).
>>
>>
>> Dimensions:
>>
>> 18cm long x 1.5cm dia.
>>
>> weight:
>>
>> 200.5g
>>
>> Brief description:
>>
>> Examination of the cross section shows an annular accicular crystalline
>> structure - each ring being approximatively the same thickness ~1mm, all
>> fairly regular and showing no inter growth between the rings)
>> The material has high lustre (when cleaned) and is a dark pinkish in
>> colour, it is partially covered covered with a patena of white oxide -
>> Pb?).
>> Also not magnetic, and doesn't produce a positive reaction with HCL...
>>
>> hopefully if you click/ copy the link below you should be able to see
>> three pictures (sorry the resolution isn't amazing)
>>
>> http://thehumanjourney.net/pnp/files/fsXqVBGJl/
>>
>> If anyone happens to have any ideas, views, opinions or best guesses I'd
>> very interested to know. If anyone wants more info just mail me directly:
>> [log in to unmask]
>>
>>
>> Thanks in advance
>>
>> Luke Howarth
>>
>> Géoarchéologue
>> OA Méditerranée
>> France
>
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