Carbonate Group Visible Spectra (350 - 1100 nm)
The common colored carbonate minerals are calcite, CaCO3, ankerite,
FeCO3, and rhodochrosite, MnCO3.
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
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Images of the spectra of representative carbonate minerals
yellow-brown ankerite, GRR 1282.
1.0 mm thick sample. Data Files: a, 0K; c,
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;
vibrant red rhodochrosite, GRR 1858. 1.5 mm thick sample, unpolarized spectrum from a cleavage face.
Locality not specified, but probably Colorado. 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.
no other data files
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