Glacier ice surfaces appear dark due to many light-absorbing particles (LAPs), such as mineral dust, microbial organic matter, and black carbon. In contrast, the development of a weathering crust on bare ice brightens the surface by increasing albedo. Field studies on the Potanin Glacier, Mongolia, defined a low-density surface layer as weathering granular ice. Broad-band albedo increased with this layer’s thickness but decreased with organic matter. High LAP amounts hindered crust growth.