Lead Isotope Ratio
Definition
The ratios of the radiogenic lead isotopes (206Pb, 207Pb, 208Pb) to stable 204Pb; these ratios reflect the age and uranium-thorium content of the geological source and are not altered by smelting; used to trace gold, silver, and lead artefacts to their ore-deposit source regions.
- Isotopes measured
- 206Pb, 207Pb, 208Pb relative to 204Pb
- Reflects
- Age and U-Th content of ore source
- Stability
- Unaltered by smelting
- Application
- Provenance of gold, silver, lead artefacts
Common questions
Why is smelting resistance important for provenance work?+
Melting or refining a metal chemically separates or purifies elements but does not change the ratio of one lead isotope to another within the lead present, so the isotopic fingerprint of the original ore survives industrial processing intact and can still be traced back to a source region.
How does lead isotope ratio differ from trace element analysis?+
Trace element composition can be altered by refining, alloying, or contamination during manufacture, whereas isotope ratios are a property of the atoms themselves and stay fixed regardless of those processes, making them a more reliable long-term provenance marker.
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