In Defence of Lead Isotope Analysis

By Tite, M. S. | Antiquity, December 1996 | Go to article overview

In Defence of Lead Isotope Analysis


Tite, M. S., Antiquity


The recent ANTIQUITY paper by Budd et al. (1996), 'Rethinking the quest for provenance', is the latest in a series of polemical papers on archaeometallurgy by the Ancient Metallurgy Research Group at Bradford. Having started with the appearance of arsenical copper in Britain in the Early Bronze Age (Budd et al. 1992), this series has now moved on to the application of lead isotope analysis to copper provenance studies. These papers contain very little, if any, new scientific data but instead attack established procedures and interpretations. In view of the very considerable number of journal pages that have recently been thus filled, it is time to ask what has been achieved.

The measurement of the lead isotope ratios of trace lead impurities in copper and bronze artefacts to identify the ore source for the copper was first investigated by Gale & Stos-Gale (1982). The principal advantage of this method for provenancing copper is that, on the basis of experimental tests (Barnes et al. 1978; Pernicka & Bachmann 1983), the lead isotopes can be assumed not to fractionate during the production of the copper. Therefore, the lead isotope ratios in the copper metal should be the same as those in the ore from which it was produced. This contrasts with the situation for trace element provenancing when the concentrations of the impurities carried through from the ore to the metal can vary depending on the production processes used. The different ore deposits used can be distinguished because their lead isotope ratios vary according to both the geological age of the deposit and the processes involved in its formation (Pollard & Heron 1996: 312).

A major application of the technique has been to investigate the Bronze Age trade in copper in the Mediterranean with a particular emphasis on the so-called 'oxhide' ingots. These ingots of copper, which normally weigh around 30 kg, date to the Late Bronze Age when Cyprus was a major producer of copper and are found on sites from Sardinia in the west as far as Syria in the east.

Prior to the ANTIQUITY paper (Budd et al. 1996), Budd et al. (1995a) raised again the possibility that the fractionation of lead isotopes occurred during ancient metallurgical processes and that lead isotope provenance studies were therefore invalidated. Strong reservations expressed regarding this hypothesis were subsequently proved correct by a report on a laboratory simulation of roasting which stated, but without providing numerical data, that lead isotope fractionation occurs to no measurable extent (Budd et al. 1995b). The Bradford results were to some extent anticipated by a paper at the International Archaeometry Symposium in Ankara in 1994 by Gale & Stos-Gale (1996), which demonstrated that lead isotope fractionation did not occur for silver subjected to roasting, smelting, cupellation and refining.

In the same paper, Budd et al. (1995b) suggest that tin isotopes fractionate during the melting and re-melting of bronze; so the tin isotope ratio observed in bronze could indicate the number of times that the metal has been re-melted and re-used in antiquity. Again, no prior experimental work was undertaken to provide a preliminary indication of the validity of the hypothesis.

The ANTIQUITY paper (Budd et al. 1996), in part summarizing an earlier paper in Journal of Mediterranean Archaeology (Budd et al. 1995c), expresses three areas of concern. First, many of the earlier lead isotope measurements are of insufficiently high precision; a programme of re-measurement is required, and lead isotope data-sets for ore deposits should be routinely published. Second, the geological histories of available ore sources are insufficiently unique for each ore source to have a lead isotope signature significantly different from those for all other ore sources; this problem cannot be overcome by statistical treatment. Third, the interpretation of the lead isotope data is more complex than originally conceived, particularly when possible mixing and recycling of metal from more than one source is considered. …

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this article

This article has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited article

In Defence of Lead Isotope Analysis
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.