The so-called “Gyp Hills” in south-central Kansas have earned their name, with the source of their namesake reaching below the surface.

That would be gypsum, the name given to the soft mineral — a combination of calcium sulfate and water — that has been excavated and mined in Kansas since the 1860s. The substance is used to make what is known as wallboard, the building material that forms the smooth walls of homes, offices, commercial buildings and virtually any other building around.

Gypsum is nothing new, having been used as plaster in building the Egyptian pyramids.

National Gypsum Co., which has a gypsum-collection operation and wallboard plant in Medicine Lodge, both mines and quarries gypsum rock, then crushes and grinds it before baking it to remove chemically bound water.

The company then fortifies the material with starch and other additives, including water, to form a stucco slurry. The stucco then is sandwiched between two sheets of paper, where it hardens and forms gypsum board.

Gypsum also can be used as an additive for cement, and to create Plaster of Paris and alabaster.