Lucabindiite

Chemical formula: (K,N³⁻H₄)As³⁺₄O₆(Cl,Br)

Lucabindiite is a rare potassium, ammonium, and chlorine arsenite, forming colorless, tabular crystals in volcanic fumaroles.

## Characteristics Lucabindiite is a mineral from the oxide group, specifically an arsenite. It occurs as very small, tabular crystals, reaching up to 0.2 mm in size. The crystals are colorless and transparent, with a vitreous luster. They typically form aggregates or thin coatings on rock surfaces. Due to the extremely small size of the crystals, visual features are difficult to observe without a microscope. ## Physical Properties The hardness and density of the mineral have not been determined due to the small size and rarity of the material. The crystals exhibit a vitreous luster and are transparent. The mineral does not show fluorescence under ultraviolet light. ## Colors and Varieties Lucabindiite is colorless. No colored or commercial varieties are known. ## History and Name The mineral was discovered in a fumarole of the La Fossa crater on Vulcano Island, part of the Aeolian Islands archipelago in Italy. It was approved by the International Mineralogical Association (IMA) in 2013 under the number IMA2013-032. The name honors Luca Bindi (born 1971), an Italian mineralogist and crystallographer from the University of Florence, for his contributions to mineralogy and the discovery of many new minerals, including some from the same locality. ## Uses Lucabindiite has no industrial application. Its significance is purely scientific and as a collector's item, being a very rare and unique mineralogical species.

Properties

Color: colorless to white
Luster: Vitreous
Streak: white
Density: 3.68
Fracture: None observed
Transparency: Transparent
Crystal system: Hexagonal

Diagnostic features

## Identification Practical identification of lucabindiite is impossible without advanced laboratory methods, such as X-ray diffraction (XRD) and chemical analysis (EDS). In the field or in a collection, suspicion may fall on colorless, microscopic crystals found in volcanic exhalation products, but confirmation requires specialized studies. ## Distinguishing from Similar Minerals Lucabindiite can be confused with many other colorless secondary minerals formed in fumaroles, such as arsenolite, clausthalite, or other arsenites. Differentiation relies solely on crystal structure analysis and chemical composition. ## Crystal Forms The mineral forms thin, tabular crystals with a hexagonal habit, often grouped into small aggregates or rosettes. The crystals are very small, usually not exceeding 0.2 mm.

Geological environment

## Genesis Lucabindiite is a mineral of volcanic origin, formed by sublimation from volcanic gases (exhalations) in high-temperature fumaroles. It crystallizes at temperatures of approximately 200-300°C on the surface of pyroclastic volcanic deposits. ## Mineral Associations This mineral co-occurs with other rare fumarolic minerals, such as arsenolite (As₂O₃), K-Na-sulfate, Bi-sulfides, greenockite (CdS), sphalerite (ZnS), and realgar (As₄S₄). ## Localities The only known occurrence of lucabindiite worldwide is its type locality - the La Fossa crater on Vulcano Island (Aeolian Islands), Italy.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of lucabindiite specimens is primarily assessed based on the richness and abundance of microcrystals on the rock matrix. Due to their microscopic nature, single, well-formed, and isolated crystals (though still very small) are most desired by specialized micromineral collectors. The size and aesthetics of the matrix also influence value. ## Popular Localities The only source of specimens is the type locality: the La Fossa crater on Vulcano Island in Italy. Collecting material at this location is restricted and requires special permits.

Care and storage

## Cleaning Due to its extreme rarity, small crystal size, and water solubility, lucabindiite specimens should not be cleaned by any wet methods. Dust should only be removed using a soft brush or a photographic air blower, with utmost care. ## What to Avoid Contact with water, acids, solvents, and all chemical agents must be strictly avoided, as the mineral is soluble. Specimens should be protected from moisture, high temperatures, and direct sunlight, which could cause sample degradation. It should not be subjected to ultrasonic cleaning. ## Storage Lucabindiite specimens must be stored in dry conditions, preferably in a tightly sealed container (e.g., a "perky box") away from sources of moisture. Due to its fragility and small size, vibrations and shocks should be avoided. Storage under stable room conditions is crucial for maintaining the integrity of the specimen.