Adranosite-(Fe)

Chemical formula: (N<sup>3-</sup>H<sub>4</sub>)<sub>4</sub>NaFe<sup>3+</sup><sub>2</sub>(S<sup>6+</sup>O<sub>4</sub>)<sub>4</sub>Cl(OH)<sub>2</sub>

Adranos_ite-(Fe) is an extremely rare sodium, ammonium, and iron sulfate, forming tiny, acicular crystals in volcanic fumaroles.

## Characteristics Adranos_ite-(Fe) is a sulfate mineral that visually appears as very small, acicular crystals. It typically forms small, tangled aggregates or radial clusters resembling cotton tufts. The crystals are transparent and exhibit a vitreous luster, giving them a delicate, shiny appearance despite their small size. ## Physical Properties This mineral is very brittle and soft, although its exact Mohs hardness has not been determined due to the small size and rarity of the crystals. The luster is vitreous, and the crystals are fully transparent. Density has also not been experimentally measured. ## Colors and Varieties Adranos_ite-(Fe) occurs in shades from pale yellow to yellowish-brown. Variations in color saturation depend on specific crystallization conditions. No named varieties of this mineral have been distinguished. ## History and Name The mineral was formally described and approved by the International Mineralogical Association (IMA) in 2012. Its name refers to adranos_ite, of which it is the iron (Fe) analogue – iron dominates in the structure in place of aluminum. The main name, "adranos_ite," comes from Adranus, an ancient deity worshipped in the region of Mount Etna in Sicily. The type locality and only known occurrence is the La Fossa crater on Vulcano Island, Italy. ## Applications Due to its extreme rarity and microscopic size, adranos_ite-(Fe) has no commercial or industrial applications. It is solely an object of scientific research and a prized acquisition for advanced systematic and micromineral collections.

Properties

Luster
Vitreous
Streak
White
Transparency
Transparent
Crystal system
Tetragonal

Diagnostic features

## Identification Identification of adranos_ite-(Fe) is impossible without advanced analytical methods such as X-ray diffraction (XRD) and chemical microanalysis (EDS). Preliminary identification based on visual characteristics relies on the distinctive acicular habit, yellow color, vitreous luster, and, crucially, its origin from the only known locality – the fumaroles of La Fossa crater. ## Distinguishing from Similar Minerals This mineral can be easily confused with its aluminum analogue, adranos_ite, which occurs in the same environment and has a similar appearance. Definitive distinction requires chemical analysis confirming the dominance of iron over aluminum. It can also be confused with other yellow, acicular volcanic sublimates. ## Crystal Forms Adranos_ite-(Fe) crystallizes in the form of very thin, elongated, acicular crystals. These crystals almost always occur as aggregates – tangled, woolly clusters or small radial rosettes.

Geological environment

## Genesis Adranos_ite-(Fe) is a fumarolic mineral. It forms through sublimation, crystallizing directly from hot volcanic gases rich in sulfur, ammonia, iron, and chlorine. It forms on the surface of existing rocks near high-temperature volcanic exhalations. ## Mineral Associations This mineral occurs in association with other rare sulfates and halides that form under similar conditions. Its most common associations include adranos_ite (its aluminum counterpart) and minerals from the demicheleite group: demicheleite-(Br), demicheleite-(Cl), and demicheleite-(I). ## Localities The only confirmed occurrence of adranos_ite-(Fe) in the world is its type locality – the La Fossa crater on Vulcano Island, part of the Aeolian Islands archipelago, Sicily, Italy.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of adranos_ite-(Fe) collector specimens is assessed based on several criteria. The most important is the abundance and density of crystals on the rock matrix. Specimens with clearly formed, sharp needles creating aesthetic, radial aggregates are more highly valued. An intense, pure yellow color is also desirable. Co-occurrence with other rare fumarolic minerals adds significant value. ## Popular Localities All adranos_ite-(Fe) specimens available on the collector's market come from a single location in the world: the La Fossa crater on the Italian island of Vulcano. This is the only source of this mineral.

Care and storage

## Cleaning Specimens of adranos_ite-(Fe) are extremely delicate and potentially water-soluble. Absolutely no water or chemical liquids should be used for cleaning. The only safe method for dust removal is very careful use of compressed air from a safe distance. ## What to Avoid Avoid contact with water, moisture, acids, and all cleaning agents. The mineral is sensitive to shocks and mechanical damage – even touch can destroy the tiny crystals. It should also be protected from sudden temperature changes. ## Storage Specimens should only be stored in specialized, tightly sealed micromineral boxes (so-called micromounts). Protect from dust, vibrations, and direct sunlight. A stable, dry environment is best.

Sources

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