Lead is present in the Chalcolithic slags from Timna (0.6% - ~some %),
containing Pb in metallic ansd oxidic form. These slags are results of
copper smelting. Iron ores that was added in this period to copper ores as
flux contain a lot of  Pb. Copper ores with remnants of sulphides also
contain Pb (galena). Even in copper ingots found in the Central Negev
amount of Pb was relatively high (up to 3%). Almost all the Pb is
concentrated in sulphidic inclusions. See  B. Rothenberg (1990), Hauptmann
et al. (1992 Archeomaterials),  Segal et al. in proceedings of the
conference "Metal in antiquity" that'll be published I think before summer.
Best wishes Irina.     





At 09:53  3/29/99 +0200, you wrote:
>Does prehistoric copper slag ever contain lead in appreciable quantities?
I don't know any quantitative analyses of copper slag that  could  be used
to answer this question. On the face of it common sense says that lead
would only be added to already smelted metal, but some copper ores have a
lot of natural lead and could be a problem. 
>
>I am asking because I thought I was  going to have some ore samples
analysed for lead isotopes, but suddenly the laboratory realized that
nobody knew how much lead  there would be in them and samples with a lot of
lead would be bad for the mass spectrometer.  As a non-scientist I am a bit
out of my depth, and I would be  grateful for  help. Have bulk analyses of
that kind been made of copper slag? If so please  give references. What
other arguments should be considered. I would like  to present the
laboratory with as neutral and objective information as I can - obviously I
am not interested in dirtying up their machine. I  think basically the
geologists, some of whom may view the archaeological project with a bit of
suspicion anyway, do not know much about prehistoric copper slag and
suddenly got an idea.
>
>David Liversage, Morlenesvej 26, DK-2840 Holte, Denmark	
>
>
Dr. Irina Segal
Geochemistry Department
The Geological Survey of Israel
30 Malkhe Israel Street
Jerusalem 95501, Israel


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