Final answer:
Gypsum sand or white sand forms through the chemical precipitation of minerals from water, typically involving the transformation of anhydrite to gypsum in near-surface environments.
Step-by-step explanation:
Gypsum sand, also known as white sand, is a type of non-clastic sedimentary rock that is formed by chemical precipitation. An important mineral in the formation of gypsum sand is anhydrite, which is an anhydrous calcium sulfate mineral (CaSO4). In near-surface environments, anhydrite absorbs water to form gypsum (CaSO4ยท2H2O), which then becomes the primary constituent of gypsum sand. One common way this process occurs is in evaporite deposits, where water evaporates from a saline solution, leaving behind the dissolved minerals from the concentrated solution to precipitate and form layers of gypsum. Over time, these layers are subjected to geological processes such as compaction and cementation, which turn sediments into sedimentary rock.