SCT: How Lava Gets Into Our Teeth
From deep in the earth to our
teeth and bones, a hard mineral
lets us bite while standing up
How We Bite with Apatite: The Wonders of a Hard Mineral
by David Coppedge
Science & Culture Today, Sept 5, 2025
One of the main ingredients in our teeth that gives us a good, strong bite is a mineral containing calcium and phosphorus, called apatite. Volcanoes erupt this mineral as a component of lava. This geological supply chain serves as a leading source of phosphorus for the biosphere. But how does apatite get into our teeth? And why is it perfect for grinding and chewing our food? Herein lies another episode suitable for Michael Denton’s Privileged Species series or for the new Secrets of the Human Body series. It illustrates a fascinating role that geology plays in biology.
An apatite gemstone (Wikimedia Commons)
It’s only a coincidence that apatite and appetite are homonyms. We need apatite without an appetite for it; it is not a part of our diet, and trying to bite into it might cause pain without nourishment. The mineral was named by A. G. Werner in 1788 from the Greek word for “deceiver” because it often misled mineralogists due to its similarity to aquamarine (some forms of apatite can be made into beautiful blue gemstones). Actually, apatite stands for a class of minerals. The chemical formula is Ca10(PO4)6(X)2, where X can be the hydroxyl ion (OH–) for hydroxyapatite, fluorine ion (F–) for fluorapatite, or chlorine ion (Cl–) for chlorapatite. Other forms with this basic stoichiometry are possible by substituting other cations or anions. In apatite, note that the elements calcium (Ca) and phosphorus (P, in the form of phosphate, PO4) are its primary constituents….
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The authors [of a press release from CSIRO], though, did not tell how apatite gets from magma to teeth. Since we do not normally eat magma sandwiches, I had to dig deeper to learn more…..
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