Blue Halite records a prolonged space exposure history of the meteorite Sidi El Habib 001

Abstract Rare blue halite has been found in the H5 ordinary chondrite Sidi El Habib 001 (SEH 001). The presence of halite is the direct evidence of fluid activities on the parent body, but its blue coloration is still mystery. Here we performed comprehensive analysis of blue halite in SEH 001. The blue coloration can be explained by color centers dominated by V K -related absorptions and sodium colloids. Radioactive decay of 40 K has been widely considered as the irradiation source in terrestrial and extraterrestrial colored halite crystals. However, SEH 001 blue halite contains no KCl inclusions, and its K abundances (550–750 ppm) are much lower than those of other colored halites. Therefore, we infer that the color centers of halite in SEH 001 were introduced by space radiation during residence on the parent-body surface and/or transit to Earth. Cosmic-ray exposure ages of ~4 Ma provide a temporal framework for this irradiation record. This study provides mineralogical evidence that prolonged space irradiation can produce and preserve lattice damage in meteoritic halite. Our results also highlight the potential of color centers in halite as mineral records of radiation exposure in planetary materials and space environments.