Colors from metal ions in minerals

All of the examples of colored minerals on this page have color due to metal ions.  Ions of the first row transition elements (Ti to Cu) are normally responsible for color in these minerals.  These ions have electrons in the five 3d orbitals. In the crystallographic sites found in minerals, the 3d orbitals split into different energies. Visible light interacts with these electrons and causes them to be excited to higher energy orbitals. The wavelengths that cause these transitions are subtracted from the incident light resulting in color.

First Row Metals 

Other Metal Ions

Mineral Spectrum Mineral Photo
bastnäsite bastnäsite
monazite monazite
titanite titanite

The rare-earth elements have distinctive colors in the 3+ oxidation state and distinctive absorption spectra that change little with different hosts. Here are some examples of synthetic rare-earth garnets and phosphates.

Sample Photo  Spectrum  Sample Photo 
La - colorless
Ce(3+) - colorless   Tb Ga Garnet Tb3Ga2(GaO4)3 
Pr Ga Garnet   Dy Ga Garnet Dy3Ga2(GaO4)3 
Nd Ga Garnet Nd3Ga2(GaO4)3

Ho Ga Garnet Ho3Ga2(GaO4)3
Pm is not naturally occuring   Er Ga Garnet

Y Al Garnet

Sm Ga Garnet  Sm3Ga2(GaO4)3 Tm  
Eu Ga Garnet  Eu3Ga2(GaO4)3  Yb  
Gd - colorless   Lu - colorless  

Several of the garnets illustrated show evidence of contamination by other rare-earths - better examples to come in the future

Often asked questions about color in minerals

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last updated: 4-Sep-2023