The BCCF - for information about calcium carbonate

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Calcium Carbonate

The World's Most Versatile Mineral

Calcium Carbonate Glossary


Chalk is a poorly compacted sedimentary rock predominately composed of compacted coccoliths (a lime-secreting algae).


Formed as limestone (see below) but the sedimentation process occurs in the presence of magnesium resulting in a dolomitisation process.


Limestone is also a sedimentary rock, but it is more compacted than chalk. It is formed from the remains of microscopic animals or foraminifera.


Marble is a coarse-crystalline, metamorphic rock, which is formed when chalk or limestone are recrystallised under conditions of high temperature and pressure.

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Uses of CaCO3 from prehistory to the Middle Ages

40,000 – 10,000 BC. Cave paintings used calcium carbonate pigments

The major prehistoric use was not of the Chalk itself, but of the flints within the Chalk, which are known to have been used as tools by prehistoric man.

Prehistoric cave painting using calcium carbonare pigments

However, calcium carbonate has been detected in nearly all prehistoric cave paintings in the period between 40,000 and 10,000 BC, though it was only right at the end of this epoch that chalk and limestone powders were actually used by the caveman artists.

100AD – 5th Century. Calcium carbonate used to construct roads

Chalk, flint and gravel were used by the Romans to construct road systems. They utilised chalk in many other ways, chalk was thought to have been used in coffins to preserve bodies and was also used in cosmetics worn by Roman women.

Anglo-Saxon Britain – Middle Ages. Chalk used as a fertilser

In Roman Britain, Anglo-Saxons times and in the Middle Ages, chalk was applied to the land as a fertiliser – a practice still routinely carried out by farmers today. Regular Calcium carbonate applications help reduce soil acidity and help optimise conditions for crop growth. Old Norman leases often contained covenants to ensure that chalk was regularly applied to the land and a statute of Henry III in 1225 gave every man the right to sink a marl pit on his own land.

calcium carbonate is still used in agriculture today - a practice that goes back to Roman Britain

Other older uses for chalk in the Middle Ages include it being used for medicinal purposes in the fight against scurvy, probably unsuccessfully, and in the mid to late 14th century Welsh market traders used to try to pass chalk off as a hard cheese on unsuspecting customers, hence the popular term 'chalk & cheese'!

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