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The Archaean zircon that is the subject of Round #4 of G-Chron is being dispatched

G-Chron

— the proficiency test for age-dating of minerals

One of the few ways to know if you can trust your U-Pb data

The G-Chron Round #4 sample, a high purity Archaean zircon, is being dispatched. Closing date for submission of results: Wednesday 4th March 2026 

Round #3: G-Chron 2024 — Zircon Peng-16: Report available for download

Round #2: G-Chron 2021 — Zircon Kara-18: Report available for download

Round #1: G-Chron 2019 — Zircon Rak-17: Report available for download

The report download procedure for all active participants is given in our emails announcing the availability of G-Chron reports.

For enquiries about:

The programme and use of the website, contact Peter Webb and Michael Wiedenbeck: gchron.iag@gmail.com

Payments and subscriptions, contact Chris Jackson: iag-treasurer@virginmedia.com

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You are required to have authorisation from G-Chron before you proceed and you are strictly limited to the use set out within that authorisation. Unauthorised access to or misuse of this system is prohibited and constitutes an offence under the Computer Misuse Act (UK) 1990.
Your use of this website is subject to the terms and conditions of participation in G-Chron. By continuing you imply your acceptance of these terms and conditions.

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If your contact details have changed please update them. If your contact status or that of your colleagues has changed please email us, quoting your G-Chron account number.

G-Chron Organisers for the International Association of Geoanalysts:

Michael Wiedenbeck (Potsdam, Germany) Principal Organiser
Peter Webb (Milton Keynes, UK) Website Administrator
Chris Jackson (Ashford, UK) Subscriptions Manager

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