Why do windblown sand grains often look rounded and frosted?

Windblown sand grains often appear rounded and frosted due to the intense and prolonged nature of eolian (wind-driven) abrasion in desert environments.12

• Rounding: As sand grains are transported by the wind, they frequently collide with one another and with the surface. This process of constant impact wears down the edges of the grains, eventually shaping them into nearly spherical forms. This rounding occurs much more rapidly in wind-transported sands than in those moved by water. Coarser grains typically become better rounded than finer ones because they strike surfaces more frequently and with greater force during transport.2
• Frosting: The frosted appearance is caused by minute pitting on the surface of the grains. These tiny pits are the result of the high-energy collisions and abrasive action that occur as grains are moved by the wind.12

These textural characteristics are so distinct that they are often used by geologists to identify sandstone that formed in ancient desert dune environments.2