Structural formulas of two glycosides. (a) Methyl β-\scd-glucopyranoside. (b) Lactose, 4-O-β-\scd- galactopyranosyl-\scd-glucopyranose; the wavy bond indicates that the group may have various orientations in space.
The uranium-containing mineral uraninite appears as the dark streaks in this rock sample. The mineral used to be called pitchblende on account of its dark coloration. (Credit: Wyoming State Geological Survey)