Historical Background Calcium was isolated by Sir Humphrey Davy in 1808, but it was known long before that in its crystalline forms. Iceland spar was scientifically described in the late 17th century, and was the material that gave R.J. Hauy clues in developing the theory of crystal structure, leading to modern structural crystallography. Calcium Carbonate When combined as calcium carbonate the element takes the form of limestone, chalk, eggshells, coral, etc. Natural forms of calcium carbonate are generally contaminated with clay and other impurities. White limestone is a relatively pure form of the mineral in nature, while Iceland spar is a tightly crustallized form that has useful optical properties.
Calcium carbonate is also an important contributor to some geological changes.
It is soluble in water that contains carbon dioxide, and thus contributes to the erosion of limestone deposits. It can then be deposited elsewhere. Notable examples of this action are at Carlsbad Caverns in New Mexico and Luray caverns in Virginia. The stalactites and stalagmites are primarily limestone. Although widely available in various natural forms, modern laboratory, electronic and ceramic applications require the use of synthetically prepared material, for its higher purities and more reliable properties.