While elemental fluorine is highly reactive, its compounds can be quite stable. It was realised centuries ago that fluorides contained an as yet unidentified element similar to chlorine - many scientists died trying to isolate fluorine from these compounds (the fluorine martyrs). Henri Moissan eventually achieved this, for which he got the Nobel Prize in 1906. Many materials adopt the same atomic arrangement as Fluorite and this structure type is fundamental in our understanding of their properties - many fluorites give off light i.e. they are 'fluorescent'! Fluoride is considered essential for healthy teeth and bones, but only in small amounts, and it is added to drinking water and toothpaste. When you brush your teeth crystals are formed that make them more resistant to acid (which generally makes the tooth porous and prone to decay).
More info about the International Year of the Periodic Table (IYPT) in crystals project:
This project (#IYPTCrystals) is part of the International Year of the Periodic Table celebration (#IYPT2019), read more about the project here. You can follow us on social media using #IYPTCrystals and learn more about the wonders of crystals by following the CCDC on Twitter @ccdc_cambridge on Facebook ccdc.cambridge, on Instagram ccdc_cambridge or on YouTube CCDCCambridge.
If you want to find out more about some of the terms and concepts we have a Frequently Asked Questions Page.