Angarfite

Chemical formula: NaFe<sup>3+</sup><sub>5</sub>(PO<sub>4</sub>)<sub>4</sub>(OH)<sub>4</sub>·4H<sub>2</sub>O

Angarfite is a rare phosphate mineral, forming aggregates of small, tabular crystals with a characteristic reddish-brown color.

## Characteristics Angarfite is a hydrated sodium iron phosphate. It occurs as very small, thin, tabular crystals, which typically form rosette-like or spherical aggregates and crusts. Individual crystals rarely exceed 0.2 mm, and entire aggregates reach sizes up to 1 mm. Due to the small size of the crystals, its visual features are difficult to observe without magnification. ## Physical Properties Crystals exhibit a luster described as vitreous to slightly pearly on cleavage surfaces. The mineral is translucent. Its hardness and density have not been precisely measured due to the nature of the material. ## Colors and Varieties Angarfite has a characteristic reddish-brown color. No varieties have been distinguished. ## History and Name The mineral was approved by the IMA in 2012. Its name comes from the discovery locality – the Angarf-Sud pegmatite, located in the Souss-Massa region of Morocco. It was described by a team of mineralogists led by Chiara Pinucci. ## Uses Angarfite has no industrial application. It is solely an object of interest for collectors specializing in rare minerals and micromounts.

Properties

Mohs hardness
3
Luster
Vitreous
Streak
Light brown
Density
3.13
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Translucent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of angarfite under amateur conditions is practically impossible and requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS). Preliminary identification is based on its characteristic form (small, tabular crystals in rosette-like aggregates), reddish-brown color, and co-occurrence with other rare phosphates in pegmatites. ## Distinguishing from Similar Minerals It can be confused with other microcrystalline, secondary iron phosphates, such as strengite, rockbridgeite, or dufrenite. Differentiation without specialized equipment is impossible. Chemical analysis confirming the presence of sodium is crucial. ## Crystal Forms It forms thin, tabular crystals with a hexagonal outline, grouped into rosettes, spherical aggregates, and crusts.

Geological environment

## Genesis Angarfite is a secondary mineral that forms as a result of hydrothermal processes in the late stage of crystallization of granitic pegmatites. It forms in rock cavities, crystallizing from solutions rich in phosphorus, sodium, and iron. ## Mineral Associations This mineral co-occurs with other phosphates, such as strengite, rockbridgeite, dufrenite, cyrilovite, as well as with quartz, muscovite, and goethite. ## Localities The only confirmed locality of angarfite in the world is its type locality – the Angarf-Sud pegmatite near Tazenakht, in the Souss-Massa region of Morocco.

Rarity

Very rare

For collectors

## Quality Criteria The quality of angarfite specimens is assessed primarily based on the richness and definition of crystal aggregates. Specimens with clearly formed, undamaged crystal rosettes, densely covering the rock matrix, are most valued. Contrast with a light background (e.g., quartz) also enhances visual appeal. ## Popular Localities All specimens available on the collector's market come from a single location in the world: the Angarf-Sud pegmatite in Morocco.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Contact with water is not recommended due to the delicacy and small size of the crystals, which may suffer mechanical damage. ## What to Avoid Avoid contact with any chemicals, ultrasonic cleaners, and sudden temperature changes. Fragile crystals are susceptible to mechanical damage with the slightest touch. ## Storage It is recommended to store specimens exclusively in specialized "micromount" boxes, which protect them from dust, shocks, and direct contact. Avoid exposure to direct sunlight, although there is no evidence of fading.

Sources

Read more