Fluorowardite

Chemical formula: NaAl<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>F<sub>2</sub>(OH)<sub>2</sub>·2H<sub>2</sub>O

Fluorowardite is a rare phosphate mineral of the wardite group, forming small, vitreous crystals, usually in association with other phosphates.

## Characteristics Fluorowardite is a hydrated sodium and aluminum phosphate belonging to the wardite group. It occurs as very small, tabular or pyramidal crystals, rarely exceeding 0.5 mm. It typically forms rosette-like or spherical aggregates. It is a transparent mineral with a vitreous luster. ## Physical Properties Fluorowardite crystals exhibit a hardness of about 5 on the Mohs scale. Their density is estimated at 2.81 g/cm³. The mineral is brittle and has an uneven fracture. ## Colors and Varieties Fluorowardite is most often colorless, less frequently pale blue or greenish. No varieties have been distinguished. ## History and Name The mineral was first described in 1996 by I.V. Pekov, O.V. Petersen, A.V. Voloshin, and T.V. Burova. Its name refers to its chemical composition – it is an analog of wardite with dominant fluorine (Latin: *fluo* - to flow) in place of the hydroxyl group. ## Uses Fluorowardite has no industrial application. It is solely an object of interest for collectors specializing in rare minerals and micromounts.

Properties

Mohs hardness
5
Luster
Vitreous
Streak
White
Density
2.81
Cleavage
Good on {001}
Fracture
Uneven
Transparency
Transparent
Crystal system
Tetragonal

Diagnostic features

## Identification Identification of fluorowardite is possible almost exclusively using advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). Visually, it is practically indistinguishable from wardite and other similar phosphates. ## Distinguishing from Similar Minerals Fluorowardite is visually indistinguishable from wardite. It differs from wardite by the dominance of fluorine over the hydroxyl group. It can also be confused with other microcrystalline phosphates, such as wardite, crandallite, or wavellite. Certain differentiation requires specialized laboratory tests. ## Crystal Forms It forms small, tabular crystals with a tetragonal-pyramidal or dipyramidal habit. Crystals often occur in rosette-like, radial, or spherulitic aggregates.

Geological environment

## Genesis Fluorowardite is a secondary mineral, formed in the oxidation zones of ore deposits or in phosphate deposits. Its formation is associated with the activity of hydrothermal solutions in the late stages of pegmatite crystallization, where they interact with previously crystallized phosphate minerals. ## Mineral Associations It most commonly co-occurs with wardite, eosphorite, montebrasite, apatite, crandallite, goyazite, and quartz. ## Localities The most important occurrences of this mineral include the Tip Top Mine in Custer County (South Dakota, USA), where it was discovered; Mount Koashva on the Kola Peninsula in Russia; and also the vicinity of Hagendorf in Bavaria (Germany).

Rarity

Very rare

For collectors

## Quality Criteria The quality of fluorowardite specimens is primarily assessed based on the richness and aesthetics of the crystal aggregates. The most prized specimens are those with well-formed, sharp crystals forming visually attractive groups, especially in contrasting juxtaposition with associated minerals. Color, though rare, also increases value – pale blue specimens are more sought after than colorless ones. Due to the microscopic size of the crystals, the quality of the specimen under magnification is crucial. ## Popular Localities The most known and valued specimens come from the type locality – the Tip Top Mine in South Dakota, USA. Specimens from this location are considered classic for this mineral.

Care and storage

## Cleaning Specimens should be cleaned exclusively with compressed air or very carefully with a soft brush. Due to the small size of the crystals and their fragility, contact with water and any chemical agents should be avoided. ## What to Avoid Avoid ultrasonic cleaners, sudden temperature changes, and contact with acids and detergents, which can damage or destroy delicate crystals. ## Storage It is recommended to store specimens in specialized "micromount" boxes, which protect them from dust, moisture, and mechanical damage. Direct exposure to sunlight should be avoided.

Sources

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