Fluorphosphohedyphane

Chemical formula: Ca₂Pb₂+₃(PO₄)₃F

Fluorhedyphane is a rare mineral of the apatite group, being the fluorine and phosphate analogue of hedyphane, valued for its well-formed, hexagonal crystals.

## Characteristics Fluorhedyphane is a mineral belonging to the apatite supergroup. It forms hexagonal, prismatic crystals, which are usually small, not exceeding a few millimeters. It occurs as single, well-formed crystals or their radial aggregates. It is a transparent to translucent mineral with a vitreous luster. ## Physical Properties This mineral is characterized by a hardness of approximately 4.5 on the Mohs scale. Its density is significant, around 5.95 g/cm³, which is typical for lead-bearing minerals. The crystals exhibit indistinct cleavage. ## Colors and Varieties Fluorhedyphane is most often colorless or white. Some specimens may show a pale yellow tint. No distinct color varieties or commercial varieties have been identified. ## History and Name The mineral's name refers to its chemical composition – indicating the dominance of fluorine (Fluor) and phosphates (phospho) and its structural similarity to hedyphane (hedyphane). It was formally described as a new mineral species in 2009 by G. Della Ventura and co-authors. The type locality, from which the first described specimens originated, is the Blue Bell mine in San Bernardino County, California, USA. ## Applications Due to its rarity and small crystal size, fluorhedyphane has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals or the systematics of the apatite group.

Properties

Mohs hardness: 4.5
Luster: Vitreous
Streak: White
Density: 5.95
Cleavage: Indistinct on {0001}
Fracture: Conchoidal to uneven
Transparency: Transparent to translucent
Crystal system: Hexagonal

Diagnostic features

## Identification A key diagnostic feature is the crystal habit – hexagonal, prismatic columns, typical for minerals of the apatite group. High density, noticeable even in small specimens, is also an important clue. However, definitive identification requires advanced analytical methods, such as Raman spectroscopy or EDS analysis, due to its similarity to other minerals. ## Distinguishing from Similar Minerals Fluorhedyphane is visually almost impossible to distinguish from other colorless or white minerals of the apatite group, such as fluorapatite, hydroxylapatite, and especially from its arsenate analogues – hedyphane and fluorpyromorphite. It can also be confused with pyromorphite and mimetite, which often form similar crystals but are usually colored. Certain differentiation is possible only based on chemical analysis. ## Crystal Forms Crystals are typically simple, having a habit of short or elongated hexagonal prisms. They are often terminated by flat basal faces (pinacoid). They occur as single crystals or form small, radial or acicular aggregates growing on the host rock.

Geological environment

## Genesis Fluorhedyphane is a secondary mineral, forming in the oxidation zones of polymetallic ore deposits, especially those rich in lead. It forms as a result of the alteration of primary lead minerals in an environment rich in phosphorus and fluorine. ## Mineral Associations This mineral co-occurs with other secondary lead minerals. At the type locality (Blue Bell mine, USA), it was found in association with cerussite, hydrocerussite, anglesite, wulfenite, as well as its arsenate analogues – hedyphane and mimetite. ## Localities The most important and best-documented occurrence of fluorhedyphane is its type locality – the Blue Bell mine in Baker, San Bernardino County, California, USA. It is a very rare mineral, and reports of its occurrence in other places around the world are few and require confirmation.

Rarity

Very rare

For collectors

## Quality Criteria Most valued by collectors are specimens with sharp, well-formed, and transparent crystals that contrast with the color of the host rock. Crystal size is important – specimens exceeding a few millimeters are exceptionally rare and sought after. Rich crystal groups and associations with other rare secondary minerals also enhance attractiveness. ## Popular Localities The only commercially significant and known source of collectible specimens is the Blue Bell mine in California, USA. Practically all specimens available on the market come from this single locality.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. Brief rinsing in distilled water is permissible, followed by thorough drying. Ultrasonic cleaners should be avoided, as they can damage delicate crystals. ## What to Avoid The mineral is sensitive to strong acids, which can damage it. Contact with household and laboratory chemicals should be avoided. It should not be heated or exposed to sudden temperature changes. ## Storage Collectible specimens of fluorhedyphane, due to their small size and fragility, are best stored in enclosed “micromount” boxes, which protect them from mechanical damage and dust. It is not sensitive to sunlight.

Sources

IMA Mineral List (CNMNC)