Carbonate Group Visible Spectra (350 - 1100 nm)

The color of calcite can be due to its iron content which is present as Fe²⁺, to Mn²⁺, to radiation damage centers which often involve rare-earth or other elements, or occasionally to other elements such as Co²⁺ in what is commonly called cobaltian calcite.

Siderite owes its color to Fe²⁺

The color of rhodochrosite is due to its Mn²⁺ content. Most minerals with Mn²⁺ in six-coordination are pale pink. Because Mn²⁺ does not absorb light strongly, a mineral must have a high Mn²⁺ concentration to be strongly colored by Mn²⁺. Because some rhodochrosite specimens have a high degree of transparency, light can penetrate deep into the crystal and be highly absorbed in the appropriate wavelengths. 

Images of the spectra of representative carbonate minerals

• yellow-brown ankerite, GRR 2808. Plotted as 1.0 mm thick. Styria, Austria sample.

• pink calcite, GRR 1817. 30.9 mm thick sample; spectrum from a cleavage face polarized in the direction of maximum pink color. Undisclosed Mexican locality. This variety of calcite is known as Terlingua-type calcite because of its pink color and strong fluorescence under ultraviolet light. It is reported to contain the rare earth element, europium. Data Files: a;
• Blue calcite, GRR 3008. 2.72 mm thick sample, , unpolarized from a cleavage face. Crestmore, Riverside County, California, 

• Blue dolomite, GRR 3005.  0.378 mm thick sample,  unpolarized from a cleavage face. Union Company Reef, Maldon, Victoria, Australia. Museum Victoria M1036.

•  red rhodochrosite, GRR 1858. 1.5 mm thick sample, unpolarized spectrum from a cleavage face of a vibrantly red crystal. . Locality not specified, but probably Colorado. Data Files: a, 0K;

• yellow-brown siderite, GRR 2810.  Plotted as 1.0 mm thick. Tsumeb, Namibia.

Link to references to spectroscopy of calcite

Link to references to spectroscopy of magnesite

Link to references to spectroscopy of rhodochrosite

Link to references to spectroscopy of siderite

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