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Gypsum

 

Gypsum (CaSO4·2H2O) (Fig. 9) is an industrial mineral that is found in many areas in Cyprus with large deposits occurring within sediments around the Troodos range, in a narrow belt at the southern foot of the Pentadaktylos Range and also in small lenses and as a secondary mineral related to the sulphide ore bodies.  Many of these deposits are on the surface making their exploitation easy and inexpensive.  The calcium sulphate content ranges between 95% and 99%.  The thickness of gypsum reaches 150 m (Kalavasos Formation). 

 

Gypsum is one of the evaporite minerals, which is formed from the evaporation of seawater.  Such conditions of evaporation occurred in Cyprus and in the entire Mediterranean Sea some 20 million years ago, when the Gibraltar Strait closed due to the movement of the African and Eurasian lithospheric plates, thus making the Mediterranean Sea a closed basin with higher rates of evaporation than water influx.

 

Gypsum is soft (the second mineral in Mohs hardness scale) and occurs in a variety of forms such as laminated micro-crystalline layers, selenite crystals, alabaster etc.  It is appreciably soluble in water, often causing karstic phenomena (dissolution and development of voids or caves called sinkholes) in association with the deposits.

 

Gypsum has been used as a construction material for centuries.  Archaeological excavations in the western part of the island (Ambelikou village) as well as in the eastern part of the island (Salamis) revealed that gypsum was used since 4000 BC.  Its original treatment (roasting) was done in primitive kilns.  Gypsum has a variety of uses including ceiling and wall decorations, heat insulation, medicine, dentistry, art, agriculture, metallurgy etc.  After 1950, an industrial unit was formed in Cyprus producing gypsum boards.  This unit lasted for less than 10 years because there was a prejudice at that time against gypsum.  Gypsum is produced today in Cyprus in the form of plaster and filler.  A significant amount of gypsum is also used for the production of cement.  It is mechanically excavated from open pits and transported to the factories by truck for further processing. The raw gypsum for calcinations and the cement additive is then crushed and ground.

 

 

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