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It’s in the walls and ceilings of most homes, and maybe beneath the floors. Aside from being surrounded by it, most people even ingest a little of it every day.
Relax. It’s just gypsum — one of the most amazing, versatile, and useful minerals in the world. That a rock formed beneath the earth’s surface some 140 million years ago is now being used in so many divergent applications is truly amazing.
The use of gypsum as a building material dates back about five thousand years, to the ancient Egyptians. The walls of Pharaoh Cheops’s tomb within Egypt’s largest pyramid were covered with gypsum plaster.
The Egyptians were among the first to discover gypsum’s unique working properties. They learned that when a gypsum rock is crushed and then heated, most of the water present in the mineral is released as steam. The resulting material, now called “stucco,” can be easily restored to its original state by simply re-adding water. As water is added to the stucco powder, a “slurry” is formed that can be molded into virtually any shape before the material hardens back into a rocklike state.
Taking advantage of this unique feature, the Egyptians applied gypsum slurry — or plaster — over the stone walls of the pyramids to smooth interior surfaces and create a mortar to seal cracks and holes. In subsequent centuries, gypsum plaster was used to create architectural detailings, statuary, and artwork, although its use as a building material was limited.
In the United States, gypsum wasn’t used until 1785, when Ben Franklin “discovered” gypsum while traveling in France. The American statesman was fascinated with the material, then known as “Plaster of Paris.” He introduced the product to the United States, noting its usefulness in casting and soil nutrition.
Even with all these applications, gypsum supplies remain plentiful. The mineral is neither rare nor endangered. Furthermore, the gypsum board manufacturing process is extremely efficient. Approximately 95 percent of the raw materials entering a gypsum board manufacturing plant leave as finished product. |
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