New explanation for Mercury’s dark surface

Peering into space, the surface of Mercury appears dark and unreflective, an observation that has long puzzled planetary scientists due to the planet’s very low surface abundance of iron (less than 2 percent).

Iron is an important darkening material in airless bodies like the moon and asteroids.While the intense space weathering environment on Mercury, which efficiently converts the small amount of available iron into submicroscopic metallic iron, contributes to its dark surface, this effect is not sufficient to explain observations of Mercury’s appearance. As a result, researchers have long speculated that a “mystery darkening agent” must be contributing to Mercury’s dark surface.

https://www.llnl.gov/news/new-explan...s-dark-surface