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.
• yellow-brown siderite, GRR 2810.  Plotted as 1.0 mm thick. Tsumeb, Namibia.
  
• 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, 23K;
• 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;
• 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.

Data Files

• no other data files

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