Rhodochrosite is a manganese carbonate mineral with chemical composition MnCO<sub>3</sub>. In its pure form (rare), it is typically a rose-red colour, but it can also be shades of pink to pale brown. It streaks white, and its Mohs hardness varies between 3.5 and 4.5. Its specific gravity is between 3.45 and 3.6. The crystal system of rhodochrosite is trigonal, with a structure and cleavage in the carbonate rhombohedral system. The carbonate ions () are arranged in a triangular planar configuration, and the manganese ions (Mn<sup>2+</sup>) are surrounded by six oxygen ions in an octahedral arrangement. The MnO<sub>6</sub> octahedra and CO<sub>3</sub> triangles are linked together to form a three-dimensional structure. Crystal twinning is often present. It can be confused with the manganese silicate rhodonite, but is distinctly softer. Rhodochrosite is formed by the oxidation of manganese ore, and is found in South Africa, China, and the Americas. Quality banded specimens are often used for decorative stones and jewellery. Due to its softness and perfect cleavage it is rarely found faceted in jewellery and is also sought after by many collectors.

Manganese carbonate is extremely destructive to the amalgamation process historically used in the concentration of silver ores, and were often discarded on the mine dump.

Culture

Rhodochrosite is Argentina's "national gemstone". Colorado officially named rhodochrosite as its state mineral in 2002.

It is sometimes called "Rosa del Inca", "Inca Rose" or Rosinca.

<gallery widths="200" heights="200">

File:The Searchlight Rhodochrosite Crystal.jpg|"The Searchlight," a large red rhodochrosite from Sweet Home Mine, Alma, Colorado<!-- DO NOT LINK, see MOS:GEOLINK for further guidance -->, U.S.

File:Fluorite-Quartz-Rhodochrosite-ed10a.jpg|Rhodochrosite with fluorite, tetrahedrite and quartz.

File:Rhodochrosite Pink Form.jpg|Rhodochrosite from Silverton, Colorado, U.S.

File:Alma King rhodochrosite.jpg|The Alma King is the largest known rhodochrosite crystal; it was found in the Sweet Home Mine near Alma, Colorado and donated to the Denver Museum of Nature and Science.

File:Rodocrosita 2.jpg|Exhibit in La Plata Museum, Argentina.

File:The Alma Rose.jpg|The Alma Rose specimen from the Sweet Home Mine. On display at the Rice Northwest Museum of Rocks and Minerals in Hillsboro, Oregon, U.S.

File:Rhodochrosite Argentina.jpg|Rhodochrosite from Argentina

</gallery>

See also

  • List of minerals
  • Manganoan calcite

References

  • Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., .