Mineral dendrites: Indicators for geological aqueous environments

Mineral dendrites—branched, black-to-reddish patterns commonly found in rocks—have received limited attention in the geosciences, despite their striking appearance. In this review, we trace the study of mineral dendrites from early observations to modern numerical simulations. We demonstrate that dendrite growth is closely coupled to the surrounding aqueous environment, with their morphology highly sensitive to the physical and chemical conditions during formation. It is thus suggested that mineral dendrites can serve as effective tracers for the evolution of the aqueous environment, indicating the concentration of reacting species and the history of fluid pulses. These characteristics make mineral dendrites an excellent natural laboratory for investigating non-classical crystallization and active environmental remediation in nature. Notably, the dendritic rocks observed on Mars by the Curiosity Rover suggest that terrestrial dendrites may serve as analogues for understanding Martian paleo-environments. Future work may elucidate the dynamics of mineral dendrite evolution through correlations between trace element distributions and dendrite growth in diverse geological settings.