Biotite

A common dark mica. Symbolizes spiritual support.

Trivia

 * Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula K(Mg,Fe)3AlSi3O10(F,OH)2. It was named by J.F.L. Hausmann in 1847 in honor of the French physicist Jean-Baptiste Biot who, in 1816, researched the optical properties of mica, discovering many unique properties.