LAUSR

Description Zircon s reveal the geochemistry of Earth’s earliest hydrothermal systems To search for life on other worlds, understanding the prebiotic chemistry of those worlds is necessary (1). However, to know which organic compounds form in the absence of life, and the conditions conducive for life’s emergence, requires an understanding of the geochemical environment (e.g., fluid salinity, metal availability, etc.) in which those compounds existed. As Earth is the only example for life, origins-of-life studies simulating early Earth conditions can inform this endeavor. Unfortunately, the geological record of early Earth is sparse, and the constituents of ancient rock specimens have been heavily altered over time. Consequently, the fluid geochemistry of prebiotic environments on early Earth remains uncertain. On page 582 of this issue, Trail and McCollom (2) report that zircons—natural silicate minerals in Earth’s crust—can constrain the fluid geochemistry of ancient hydrothermal systems. This provides a potential path to unraveling the fluid composition of early Earth and discerning life’s origins.