White colored stream stone coatings with a peculiar geochemical signature found in a high mountain stream

Peculiar coatings rich in arsenic, copper, nickel, uranium, and yttrium were found to cover stream stones in a high mountain stream downstream of the confluence of small acidic tributaries, which emerge at the front of the Krummgampen rock glacier (Kaunertal, Ötztal Alps, Tyrol, Austria). The hard mineral coatings are characterized by a white color, a x-ray amorphous structure and tjhey showed properties of hydrous aluminium silicates like allophane and/or imogolite. Main constituents of these stream stone coatings are aluminium, silica, and sulfur.