Function

• Calcium fluoride, also known as the mineral fluorite, can react with strong acids to produce hydrofluoric acid, a dangerous chemical that etches glass and has many manufacturing uses. Manufacturers of metals, jewelry, and organofluorine compounds all use fluorite for various purposes, according to the Illinois State Geological Survey.
  
  

Identification

• Calcium fluoride appears as a colorless solid in its pure form; the mineral as found in nature often contains purple and green banding or coloration, sometimes yellow or blue shades. Most often it appears as a semi-translucent, cloudy and colorful stone, relatively soft with a Mohs hardness of 4.
  
  

Features

• Calcium fluoride, as a chemical compound, features ionic bonding: The calcium atom loses two electrons, and each fluorine atom gains one, making them more stable than in their base state. Therefore, its chemical formula is CaF2: one calcium atom and two fluorine atoms, although in practice this material forms units of multiple molecules, according to Loyola University Chicago.
  
  

Ionization

• Calcium appears in the second row of the periodic table; fluorine appears in the second-to-last row. Elements generally ionize (gain or lose electrons) based on how similar they are to the last-row noble gases, according to Prof. Armen Zakarian at Florida State University.
  
  An element in the second row ionizes by losing two electrons; an element in the second-to-last row ionizes by gaining one electron. Therefore, calcium gives away one electron to each fluorine atom.
  
  

Fun Fact

• Although calcium fluoride does not make good rings because of its lack of hardness, jewelry-makers often use it in necklaces.