Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than s
Sand dunes in the Idehan Ubari, Libya
Depiction of sands: glass, dune, quartz, volcanic, biogenic coral, pink coral, volcanic, garnet, olivine. Samples are from the Gobi Desert, Estonia, Hawaii and the mainland United States. (1×1 cm each)