Gypsum (CaSO4•2H2O) is a representative member of the sulfate mineral class where metal cations bond with the sulfate (SO4)2-anion. These crystals formed over hundreds of thousands of years as calcium from nearby limestones interacted with groundwater rich in sulfide ions from neighboring ores and heated by a subterranean magma chamber. Gypsum (which can also be a sedimentary rock) has many uses for society. Which of the following is not a common use of gypsum? a. wallboard/drywall for homes
b. a primary ingredient for toothpaste
c. surgical splints and casts
d. pH reducing agent for acidic soils