Gypsum is used in a wide variety of applications info Chemical Man

Gypsum is used in a wide variety of applications:

Gypsum board is primarily used as a finish for walls and ceilings and is known in construction as drywall, wallboard, sheetrock or plasterboard.
Gypsum blocks are used as concrete blocks in building construction.
Gypsum mortar is an ancient mortar used in building construction.
Plaster ingredients are used in surgical splints, casting molds and modeling.
Fertilizer and soil conditioner: In the late 18th and early 19th centuries, Nova Scotia gypsum, often referred to as plaster, was a highly sought fertilizer for wheat fields in the United States. It is also used in ameliorating high-sodium soils, such as in the Zuiderzee Works.
A binder in fast-dry tennis court clay
As alabaster, a material for sculpture, it was used especially in the ancient world before steel was developed, when its relative softness made it much easier to carve.
A wood substitute in the ancient world: For example, when wood became scarce due to deforestation on Bronze Age Crete, gypsum was employed in building construction at locations where wood was previously used.
A tofu (soy bean curd) coagulant, making it ultimately a major source of dietary calcium, especially in Asian cultures which traditionally use few dairy products
Adding hardness to water used for brewing
Used in baking as a dough conditioner, reducing stickiness, and as a baked-goods source of dietary calcium. The primary component of mineral yeast food.
A component of Portland cement used to prevent flash setting of concrete
Soil/water potential monitoring (soil moisture)
A common ingredient in making mead
In the medieval period, scribes and illuminators mixed it with lead carbonate (powdered white lead) to make gesso, which was applied to illuminated letters and gilded with gold in illuminated manuscripts.
In foot creams, shampoos and many other hair products
A medicinal agent in traditional Chinese medicine called shi gao
Impression plasters in dentistry
Used in mushroom cultivation to stop grains from clumping together
Tests have shown that gypsum can be used to remove pollutants such as lead or arsenic from contaminated waters.