Fluorcarmoite-(BaNa)

Chemical formula: Ba&#₉₇₂₃;Na₂Na₂&#₉₇₂₃;CaMg₁₃Al(PO₄)₁₁(PO₃OH)F₂

Fluorcarmoite-(BaNa) is an extremely rare mineral from the phosphate group, discovered in Brazil, distinguished by its very complex chemical composition.

## Characteristics Fluorcarmoite-(BaNa) is a very rare, complex phosphate belonging to the arrojadite group. It was approved as a new mineral species by the IMA in 2017. It occurs as small, tabular crystals up to 0.3 mm in size, forming aggregates. It is vitreous and has a light green color. ## Physical Properties This mineral is characterized by a hardness of approximately 5 on the Mohs scale. Its crystals are transparent to translucent, with a vitreous luster. The density calculated from crystallographic data is 3.31 g/cm³. ## Colors and Varieties It has only been observed in the form of light green crystals. No varieties are known. ## History and Name The mineral's name refers to its chemical composition – the dominance of fluorine (Fluor), barium, and sodium (BaNa) – and its connection to carmoite, another mineral from the same locality. It was discovered in the Alto do Giz pegmatite, in the Equador region, Rio Grande do Norte state, Brazil. It was described by a team of mineralogists led by Nikita V. Chukanov in 2018.

Properties

Mohs hardness: 5
Color: yellow–orange
Luster: Vitreous
Streak: yellow–orange
Density: 3.31
Cleavage: Good on {010}
Fracture: None observed
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of this mineral is possible only through advanced analytical methods, such as Raman spectroscopy, electron microprobe (EDS/WDS), and X-ray diffraction (XRD), due to its extreme rarity and small size. Visual identification in the field or in a collection is practically impossible. ## Distinguishing from Similar Minerals It can be confused with other green, microcrystalline phosphates found in pegmatites, such as other minerals from the arrojadite group. Certain differentiation requires specialized chemical analysis to confirm the unique combination of barium, sodium, calcium, magnesium, and aluminum in its composition. ## Crystal Forms It forms small, tabular crystals, usually grouped into irregular aggregates.

Geological environment

## Genesis Fluorcarmoite-(BaNa) forms in complex, granitic pegmatites rich in phosphates. It is a product of late-stage crystallization in an environment rich in barium, sodium, and fluorine. ## Mineral Associations It co-occurs with minerals such as quartz, microcline, albite, muscovite, as well as rarer phosphates, including other minerals from the arrojadite group. ## Localities The only confirmed locality for this mineral worldwide is its type locality – the Alto do Giz pegmatite, Equador municipality, Rio Grande do Norte state, in northeastern Brazil.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" mineral, its collector value primarily depends on the confirmation of its identity by a reputable laboratory. The most valuable specimens are those with well-formed, albeit microscopic, crystals, clearly visible on the rock matrix. Color and clarity are of secondary importance compared to the mere fact of possessing a documented specimen. ## Popular Localities The only source of specimens is the Alto do Giz pegmatite in Brazil, which makes every specimen from this locality extremely desirable for specialized collectors of rare minerals.

Care and storage

## Cleaning Due to its extreme rarity and small crystal size, mechanical cleaning is not recommended. If necessary, compressed air can be used to remove dust. Avoid contact with water and chemicals. ## What to Avoid Avoid ultrasonics, steam cleaners, acids, and all chemical solvents. The mineral should be protected from high temperatures and sudden temperature changes. ## Storage Specimens should be stored under stable conditions, in a closed "micromount" box, away from dust, moisture, and direct sunlight. Due to the small size of the crystals, they should be handled with utmost care.