Sand
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Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.
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)
Heavy minerals (dark) in a quartz beach sand (Chennai, India)
Sand from Coral Pink Sand Dunes State Park, Utah. These are grains of quartz with a hematite coating providing the orange color.
Granular material
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A granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact. The constituents that compose granular material are large enough such that they are not subject to thermal motion fluctuations. Thus, the lower size limit for grains in granular material is about 1 μm. On the upper size limit, the physics of granular materials may be applied to ice floes where the individual grains are icebergs and to asteroid belts of the Solar System with individual grains being asteroids.
Sand dunes