What Is Gypsum Powder?

Updated April 17, 2017

From pyramids to toothpaste, gypsum rock (ground into powder form for some uses) is essentially a nonmetallic mineral known as calcium sulphate. Due to its water content (79.1 per cent calcium sulphate to 20.9 per cent water), gypsum earned the name hydrous calcium sulphate. In pure form it is a white colour. But other gypsum colours -- brown, grey, pink and almost black -- exist due to impurities in the rock form.


The Association of Lifecasters International dates gypsum's first known historical use as early as 5,000 years ago, when it was burnt by Egyptians before being crushed into powder form and combined with water. They used it to manufacture pyramid block jointing material. But gypsum has been around for millions of years. Gypsum powder use expanded into Greek culture and even France, where a byproduct of gypsum powder is known as plaster of Paris.


Gypsum names include alabaster, from the Assyrians, who used it for statue formation. It has been called selene, after the Greek's moon goddess, and was used in temples as a glass substitute before the invention of glass. That is where we get the name selenite from for gypsum. And there is the French name: plaster of Paris.

Water Requirements

Gypsum should be mixed with the purest water available to the user. Drinking water will suffice in this regard. Once gypsum has been mixed with water, it should be kept at room temperature for use, which is approximately 21.1 degrees C. The length of time spent mixing gypsum and water will determine the overall strength of the product produced.


Gypsum powder was used as soil fertiliser, primarily, until the late 1800s, but it is still used in the 21st century to help with peanut growth and also carries the name "land plaster." It is also used for stucco work, building ornamentation, interior wall plaster and wallboard, medical splints, toothpaste, as a component in your match head, for dishes you eat out of and the chalk your child's teacher uses, as well as some metal parts on your vehicle. Gypsum is also used for casting, moulding and pottery plaster. It is made into gypsum cement for use in creating figurines. Combined with other materials, gypsum can be used in a variety of other ways, including clay forming machinery, jiggering moulds and slip casting.

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About the Author

Holly Huntington's writing has been published online by eHow.