Chemical bonds are the electrical forces of attraction that hold atoms or ions together to form molecules. Different types of chemical bonds and their varying intensity are directly responsible for some of the physical properties of minerals such as hardness, melting and boiling points, solubility, and conductivity. Chemical bonds also influence such other properties as crystal symmetry and cleavage. Stronger bonds between atoms make them more difficult to separate and, in general, stronger chemical bonds result in greater hardness, higher melting and boiling points, and smaller coefficients of expansion. There are four principal types of chemical bonds found in minerals: ionic, covalent, metallic, and van der Waals.

An ionic bond is the result of the electrostatic attraction between two oppositely charged ions. Ionic bonds exist because some elements tend to capture or lose one or more electrons resulting in a...