Rhodochrosite is a

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

carbonate mineral Carbonate minerals are those minerals containing the carbonate ion, . Carbonate divisions Anhydrous carbonates *Calcite group: trigonal **Calcite CaCO3 **Gaspéite (Ni,Mg,Fe2+)CO3 **Magnesite MgCO3 **Otavite CdCO3 **Rhodochrosite MnCO3 **Sider ...

with chemical composition MnCO₃. 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 The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

varies between 3.5 and 4.5. Its

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

is between 3.45 and 3.6. The crystal system of rhodochrosite is

trigonal In crystallography, the hexagonal crystal family is one of the six crystal family, crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the tr ...

, with a structure and

cleavage Cleavage may refer to: Science * Cleavage (crystal), the way in which a crystal or mineral tends to split * Cleavage (embryo), the division of cells in an early embryo * Cleavage (geology), foliation of rock perpendicular to stress, a result of ...

in the carbonate rhombohedral system. The carbonate ions () are arranged in a triangular planar configuration, and the

ions (Mn²⁺) are surrounded by six oxygen ions in an octahedral arrangement. The MnO₆ octahedra and CO₃ triangles are linked together to form a three-dimensional structure.

Crystal twinning Crystal twinning occurs when two or more adjacent crystals of the same mineral are oriented so that they share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals that are tightl ...

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 Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

, and is found in

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, and the

Americas The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...

. It is one of the national symbols of Argentina and the state of

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

. Rhodochrosite forms a complete

solid solution A solid solution, a term popularly used for metals, is a homogeneous mixture of two compounds in solid state and having a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solutio ...

series with iron carbonate (

siderite Siderite is a mineral composed of iron(II) carbonate (FeCO3). Its name comes from the Ancient Greek word (), meaning "iron". A valuable iron ore, it consists of 48% iron and lacks sulfur and phosphorus. Zinc, magnesium, and manganese commonly ...

Calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

(as well as

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

and

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

, to a limited extent) frequently substitutes for manganese in the structure, leading to lighter shades of red and pink, depending on the degree of substitution. This is the reason for the rose color of rhodochrosite.

Occurrence and discovery

Rhodochrosite occurs as a hydrothermal vein mineral along with other manganese minerals in low temperature ore deposits as in the silver mines of Romania where it was first found. Banded rhodochrosite is mined in Capillitas,

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. It was first described in 1813 in reference to a sample from Cavnic, Maramureş, present-day

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

. The name is derived from the combination of

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

words ροδόν (rodon, meaning ''rose'') and χρωσις (chrosis, meaning ''coloring'').

Use

Rhodochrosite is mainly used as an ore of

, which is a key component of low-cost stainless steel formulations, many

tool steel Tool steel is any of various carbon steels and alloy steels that are particularly well-suited to be made into tools and tooling, including cutting tools, dies, hand tools, knives, and others. Their suitability comes from their distinctive ...

s, and certain aluminium alloys. Quality banded specimens are often used for decorative stones and jewellery. Due to its softness and perfect

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 A gemstone (also called a fine gem, jewel, precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or polished, is used to make jewellery, jewelry or other adornments. Certain Rock (geology), rocks (such ...

officially named rhodochrosite as its state mineral in 2002. It is sometimes called "Rosa del Inca", "Inca Rose" or ''Rosinca''.

Gallery

File:The Searchlight Rhodochrosite Crystal.jpg, "The Searchlight," a large red rhodochrosite from Sweet Home Mine, Alma, Colorado, U.S. File:Fluorite-Quartz-Rhodochrosite-ed10a.jpg, Rhodochrosite with

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scal ...

, 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 Hillsboro ( ) is a city in the U.S. state of Oregon and is the county seat of Washington County, Oregon, Washington County. Situated in the Tualatin Valley on the west side of the Portland metropolitan area, the city hosts many High tech, high-te ...

, U.S. File:Rhodochrosite Argentina.jpg, Rhodochrosite from

References

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

External links

* {{National emblems of Argentina Carbonate minerals Manganese(II) minerals Symbols of Colorado Trigonal minerals Minerals in space group 167 National symbols of Argentina

Occurrence and discovery

Use

Culture

Gallery

See also

References

External links