Microcline reveals how a common mineral surface triggers ice formation in clouds

This study, published in Nature Communications, sheds new light on the exceptional ability of the mineral microcline to trigger ice formation in clouds. Microcline, a type of feldspar, is unusually effective at forming ice, even though it shares a similar chemical composition with other common minerals. Researchers at Bielefeld University, the University of Vienna, and the University of Helsinki have discovered that microcline's remarkable ice-nucleating properties stem from its most abundant surface—the (001) cleavage plane—rather than the rare surface features traditionally thought to be responsible.

This ordered, epitaxial growth of ice on microcline's (001) surface, where ice crystals align with the mineral's crystal lattice, is facilitated by the presence of a higher-index ice plane and a unique abundance of aluminol groups. These chemical groups stabilize initial water clusters through hydrogen bonding, a process that does not occur on sanidine, a similar mineral that requires step edges for ice formation.

The research, conducted using high-resolution atomic force microscopy and computer simulations, demonstrates that stable, widespread surfaces can play a crucial role in ice nucleation, challenging the long-held belief that only rare surface features are important. This finding has significant implications for climate research, as it suggests that even minor differences in ice formation can impact cloud properties, precipitation patterns, and the reflection of sunlight.

The study provides a fundamental understanding of why microcline is so effective at promoting ice formation, offering valuable insights for improving climate models and atmospheric research.