Honzaite

Chemical formula: Ni<sup>2+</sup><sub>2</sub>[As<sup>5+</sup>O<sub>3</sub>(OH)]<sub>2</sub>(H<sub>2</sub>O)<sub>5</sub>

Honzaite is an extremely rare, hydrated nickel arsenate, forming microscopic, green, bladed crystals.

## Characteristics Honzaite is a hydrated nickel arsenate, occurring as extremely small, bladed or acicular crystals, rarely exceeding 0.2 mm in length. It forms radial aggregates or appears as single, dispersed crystals. It is a secondary mineral, formed in the oxidation zones of nickel and arsenic ores. ## Physical Properties Honzaite crystals are transparent and exhibit a vitreous luster. Due to the microscopic size of the crystals, most physical properties, such as hardness or density, have not been precisely measured, but only calculated based on crystallographic data. The mineral is brittle. ## Colors and Varieties Honzaite has a characteristic, light green to emerald green color, typical of hydrated nickel minerals. No varieties have been distinguished. ## History and Name The mineral was approved by the International Mineralogical Association (IMA) in 2023 under the number IMA2023-033. The name honors Professor Jan "Honza" Plášil (born 1981), a Czech mineralogist and crystallographer from the Institute of Physics of the Czech Academy of Sciences, for his contribution to the mineralogy of uranium and related elements. It was discovered on the dump of the former Rovnost I uranium mine in Jáchymov, Czech Republic. ## Uses Honzaite has no industrial application. It is of purely scientific interest and is an object of interest for specialized micromineral collectors.

Properties

Luster
Vitreous
Streak
Light green
Density
3.45
Cleavage
Perfect on {010}
Fracture
Brittle
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of honzaite is possible only through advanced analytical methods, such as Raman spectroscopy, X-ray diffraction (XRD), and chemical analysis (EDS/WDS). Visually, in the field or in a collection, it is practically impossible to distinguish from other secondary, green nickel arsenates without specialized equipment. Its characteristic light green color and occurrence in association with other nickel and arsenic minerals are diagnostic clues. ## Distinguishing from Similar Minerals It can be confused with other green, secondary arsenates, such as annabergite, gersdorffite, or erythrite (nickel variety). Differentiation requires crystallographic and chemical analysis, as honzaite has a unique crystal structure and chemical composition. ## Crystal Forms Honzaite forms very small, bladed or acicular crystals, often grouped into radial or chaotic aggregates. Crystals are elongated along the [100] axis.

Geological environment

## Genesis Honzaite is a secondary mineral that crystallizes under low-temperature conditions in the oxidation zones of ore deposits. It forms as a result of the weathering of primary minerals containing nickel and arsenic, such as skutterudite or nickelskutterudite, in the presence of water. ## Mineral Associations At the type locality (Jáchymov, Czech Republic), it co-occurs with quartz, pharmacolite, erythrite, annabergite, gersdorffite, nickelskutterudite, metanováčekite, and other rare arsenates. ## Localities The only confirmed occurrence of honzaite in the world is its type locality: the dumps of the Rovnost I mine in Jáchymov, Karlovy Vary region, Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria As a micromineral, the collector's value of honzaite depends on the richness of the aggregates, the intensity and purity of the green color, and the aesthetic arrangement on the matrix. Specimens with well-formed, radial groups of crystals contrasting with quartz are most prized. Association with other rare secondary minerals is also crucial. ## Popular Localities The only source of specimens is the type locality in Jáchymov, Czech Republic. The material comes from historical mining dumps, and its acquisition is very limited.

Care and storage

## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to extreme delicacy and reactivity, any contact with water, chemical solutions, or mechanical tools should be avoided. ## What to Avoid Contact with water and high humidity must be absolutely avoided, as they can lead to dissolution or chemical alteration of the mineral. It should be protected from acids, detergents, and ultrasound. It is sensitive to elevated temperatures. ## Storage Honzaite specimens must be stored in sealed, dry containers (so-called micro-mount boxes) away from sources of moisture and direct sunlight. Storage in stable temperature conditions is recommended.

Sources

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