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. In 2007, more than 30 billion square feet (2.8 billion square meters) of gypsum panels were produced annually in North America.

“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, as well as the manufacture of titanium dioxide used in paint and other products.

Natural and synthetic gypsum have identical chemical compositions. 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.