Researchers from the Faculty of Science of the Open University, UK, and Dipartimento di Scienze della Terra della Un’iversità di Pisa, Italy, (Martin David Suttle, Luigi Folco and Cristoan Biagioni) led a new study featured on the cover of Meteoritics & Planetary Science (October 2025 issue). They performed the first oxygen isotope measurements of tochilinite, a hydrated iron sulfide by nanoSIMS. Their work focused on the Winchcombe meteorite, which came from a water-rich asteroid. Tochilinite in this sample records the earliest stages of water-rock interaction on the first generation of planetary building blocks.
Tochilinite had not been measured isotopically before, because it is a rare mineral that is rarely found as a pure phase and because its water content disturbs oxygen signals making accurate analysis challenging. The team overcame this by developing a new terrestrial standard using a pure tochilinite sample from Otamo Quarry in Finland. The results allowed a quantitative estimate of the alteration temperature on the parent asteroid: ~135 °C.