Gypsum has been used as
a building material since the construction of the ancient
Egyptian pyramids. Over the past 3,500 years or so, it has
become one of the most important minerals used in manufacturing
construction materials and many other products.
“Natural” gypsum is a benign rock
formed as calcium sulfate during the dinosaur era through precipitation
in vast inland seas throughout the world. “Synthetic” gypsum
is a byproduct generated primarily through the desulfurization
of flue gasses in fossil-fueled power plants.
Natural and synthetic gypsum have the same general
chemical composition. One hundred pounds of gypsum contain
approximately 21 pounds (or 10 quarts) of chemically combined
water. During the gypsum panel manufacturing process, the gypsum
is ground into a fine powder and heated to about 350 degrees
F, driving off three-fourths of the chemically combined water
in a process called “calcining.” The calcined
gypsum is used in producing gypsum plaster, gypsum panel products,
and other gypsum-based building materials.