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Anhydrite Facts

Anhydrite Facts
Anhydrite is an evaporate mineral that takes places in multi-layered deposits in sedimentary basins where there have been large amounts of sea water evaporated. Anhydrite is a sedimentary mineral composed of calcium, sulfur, and oxygen. It is also known as calcium sulfate. Good specimens of natural anhydrite are often sought by mineral and rock collectors. Most often, it is interbedded with limestone, gypsum, and halite and has accumulated up to hundreds of feet thick. On a much smaller scale anhydrites have been discovered on shorelines where there has been evaporated sea water. Anhydrite has also been discovered as a vein-filling mineral in various hydrothermal deposits. Anhydrite gets its name from the Greek word anhydrous which means "without water". When it comes in contact with humid conditions and groundwater, it quickly turns into gypsum. The primary use of anhydrite is for soil treatment and other construction materials.
Interesting Anhydrite Facts:
Anhydrite can be found in the cavities of trap rock and in the cap rock of salt domes.
The color of anhydrite is often colorless, white, and light shades of violet, blue, pink, gray, red, and brown.
The most distinctive physical properties of anhydrite are that it cleaves in three directions at right angles.
Because of this distinctive cleavage, anhydrite has earned the nickname of "cube spar."
Anhydrite can be somewhat of a challenge to identify when it is found in large and massive quantities.
Compared to halite, anhydrite is a little bit harder and insoluble.
Because both minerals are crushed and used as a soil treatment, anhydrite can be easily substituted for gypsum.
Since anhydrite has a high solubility, it helps benefit soil treatment very quickly.
Since gypsum is about 21% water weight, one ton of anhydrite has more calcium than that of one ton of gypsum.
Small amounts of anhydrite have been used as a drying agent in varnish, paint and plaster.
When combined with gypsum, anhydrite can be used to produce joint compound, wallboard, and plaster which all are often used in the construction industry.
Anhydrite has also been used as sulfur in the manufacturing of sulfuric acid.
For many years a synthetic anhydrite has been dried in kilns and used in the making of cement, flooring and plasters.
Synthetic anhydrite has been used as added filler in the producing of various paper products and certain plastics.
The recommendation is that anhydrite is stored in dry spaces or with silica gel. Some specimens are sold to collectors from very old collections that may actually be gypsum that has changed over time due to improper care.
Anhydrite is most often discovered in extremely dry areas and has formed from the dehydration of gypsum.
Anhydrite was believed to be discovered in 1794. However, in 1804, a German geologist named Abraham Gottlob Werner discovered and named it anhydrite. This name refers to the idea that this mineral does not contain water.


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