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⁺.

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

• GRR 1282 yellow-brown ankerite, 7K;. 1.0 mm thick sample. Data Files: a, 0K; c, 0K;
• GRR 1817 pink calcite, 6K;. 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;
• GRR 1858 vibrant red rhodochrosite, 7K;. 1.5 mm thick sample, unpolarized spectrum from a cleavage face. Locality not specified, but probably Colorado. Data Files: a, 0K;

Data Files

• no other data files

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