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