Correianevesite

Chemical formula: Fe²⁺Mn²⁺₂(PO₄)₂·3H₂O

Correianevesite is a rare, hydrated iron and manganese phosphate, forming small, transparent, brownish crystals.

## Characteristics Correianevesite is a rare mineral from the reddingite group, chemically classified as a hydrated iron and manganese phosphate. It occurs as small, well-formed crystals with a tabular or prismatic habit. Its appearance is usually inconspicuous, and specimens most often have a grayish-brown or reddish-brown color. Due to its rarity and small crystal size, it is a mineral of interest mainly to specialized collectors. ## Physical Properties This mineral is characterized by moderate hardness, measuring 3.5 on the Mohs scale. It is transparent and has a vitreous luster. Its density is approximately 3.25 g/cm³, which is typical for phosphates of similar composition. ## Colors and Varieties Correianevesite occurs in shades from grayish-brown to reddish-brown. The color variation depends on the iron to manganese ratio in the crystal structure. No named varieties of this mineral have been distinguished. ## History and Name The mineral's name honors José Correia Neves (1930–2007), professor of mineralogy and geology at the Federal University of Minas Gerais in Brazil, in recognition of his contribution to geological research in the region. The mineral was officially described and approved as a new species in 2008. ## Uses Correianevesite has no industrial application. Its significance is limited to the scientific and collecting spheres, as a rare representative of the reddingite group.

Properties

Mohs hardness
3.5
Luster
Vitreous
Streak
White
Density
3.25
Cleavage
on (010).
Fracture
Irregular/Uneven
Transparency
Transparent
Crystal system
Orthorhombic

Diagnostic features

## Identification Correianevesite can be identified by its characteristic crystal form, brownish color, vitreous luster, and occurrence in granitic pegmatites. Key diagnostic features include its hardness (approximately 3.5), density (3.25 g/cm³), and white streak. However, definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals This mineral can be confused with other members of the reddingite group, such as reddingite or phosphoferrite, from which differentiation is practically only possible by chemical analysis. It may also resemble some other brown phosphates found in pegmatites, e.g., triplite or zwieselite, which are usually harder and often opaque. ## Crystal Forms Correianevesite crystallizes in the orthorhombic system. It forms small, tabular or short-prismatic crystals, often grouped into small aggregates or druses. The crystals are usually well-formed, with visible faces.

Geological environment

## Genesis Correianevesite is a hydrothermal mineral, crystallizing in the late stages of the evolution of complex granitic pegmatites. It forms as a result of the alteration of primary phosphates, such as triphylite, under lower temperature conditions and the influence of aqueous solutions. ## Mineral Associations This mineral coexists with other phosphates typical of pegmatites. At its type locality, it was found in association with eosphorite, rockbridgeite, hureaulite, trolleite, apatite, quartz, and albite. ## Localities The only confirmed and detailed described occurrence of correianevesite in the world is its type locality - the small mine (garimpo) Cigana, located in Barra do Cuieté, in the municipality of Conselheiro Pena, in the state of Minas Gerais, Brazil.

Rarity

Extremely rare

For collectors

## Quality Criteria The most valuable specimens for collectors are those with well-formed, sharp, and undamaged crystals, exhibiting good transparency and an intense, reddish-brown color. Rich druses of small crystals on a rock matrix or in association with other contrasting minerals are particularly prized. Due to the small size of the crystals, specimens suitable for viewing under magnification (so-called microminerals) are standard. ## Popular Localities The only source of collector specimens is the type locality in Minas Gerais, Brazil. Material from this location is extremely rare on the market.

Care and storage

## Cleaning Correianevesite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its moderate hardness and potential reactivity, wet cleaning is not recommended without absolute necessity. If essential, use a small amount of distilled water and immediately dry the specimen thoroughly. ## What to Avoid Avoid contact with acids and other chemicals that may damage the mineral's surface. Do not expose it to ultrasonic cleaners or steam cleaners. The mineral is susceptible to scratches from harder materials. ## Storage Correianevesite should be stored in separate, padded boxes to prevent scratches and mechanical damage. It should be protected from dust and moisture. Exposure to direct sunlight is not recommended, although there is no data on its particular light sensitivity.

External references

Sources

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