Latest News

Round 2 of G-Chron: Sample to be dispatched during August


— the proficiency test for age-dating of minerals

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

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

The download procedure for all participants of G-Chron 2019 was detailed in a global email sent out  on 10th April 2020. If you did not receive that email, check your junk/spam traps.

Round 2: G-Chron 2021 — Zircon Kara-18

Our thanks for your patience. Due to the Covid-19 pandemic the 2020 round of G-Chron was postponed. We are now pleased to announce that G-Chron 2021, involving an Archaen zircon sample designated Kara-18, will shortly be under way with the dispatch of the sample expected during the coming August. As previously notified, all 2020 subscriptions are carried forward to 2021.

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

G-Chron Account Number

Login ID



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.

Not yet a member?     About G-Chron.    

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


Version: 1.00