Riu: Overall albedo of Ryugu is only 1.4 to 1.8%. Darkest object ever observed in solar system. Consistent 2.72 micron absorption band suggests presence of magnesium phyllosilicates. Variation in 2.72 micron feature at higher resolutions -- need closer mapping #LPSC2019

— Emily Lakdawalla (@elakdawalla) March 19, 2019