Bohuslavite

Chemical formula: Fe<sup>3+</sup><sub>4</sub>(PO<sub>4</sub>)<sub>3</sub>(S<sup>6+</sup>O<sub>4</sub>)(OH)·<i>n</i>H<sub>2</sub>O (15≤<i>n</i>≤24)

Bohuslavite is a very rare, hydrated iron sulfatophosphate, forming microscopic, yellowish-green crystals and aggregates.

## Characteristics Bohuslavite is a mineral from the phosphate group, characterized by a complex chemical composition containing both phosphate and sulfate groups. It occurs as very fine, acicular or platy crystals, which usually do not exceed several tens of micrometers in length. These crystals form radial or tangled aggregates, as well as thin coatings and crusts on rocks. Due to the microscopic size of the crystals, its features are difficult to observe without specialized equipment. ## Physical Properties Bohuslavite crystals exhibit a vitreous luster. They are flexible and elastic, which is an unusual characteristic for minerals. Hardness and density have not been precisely determined due to the microscopic size and fragility of the crystals. ## Colors and Varieties This mineral has a characteristic yellowish-green or canary-yellow color. No varieties have been distinguished. ## History and Name Bohuslavite was first described in 2016 by a team of mineralogists led by Jakub Plášil. The mineral's name comes from the town of Bohuslavice in the Czech Republic, near which the mineral's type locality is located – the waste dump of the "Rovnost" uranium mine in Jáchymov. It was approved by the International Mineralogical Association (IMA) under number 2015-110. ## Uses Bohuslavite has no practical applications. Its significance is purely scientific and collectible, as a very rare and recently discovered mineral.

Properties

Luster
Vitreous
Streak
Pale yellow
Cleavage
Perfect on {010}
Transparency
Transparent
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of bohuslavite is possible only through advanced analytical methods, such as X-ray diffraction (XRD) and chemical spectroscopy (EDS/WDS). Visually, it is a yellowish-green, microcrystalline coating, which is not a sufficient characteristic for identification. ## Distinguishing from Similar Minerals It can be confused with many other secondary phosphate and sulfate minerals of similar color and habit, such as lausenite, kornelite, or various minerals from the jarosite group. Definitive differentiation requires specialized laboratory tests. ## Crystal Forms Bohuslavite forms very fine, acicular or platy crystals that combine into radial, stellate, or haphazardly tangled aggregates. It also occurs as thin coatings and crusts.

Geological environment

## Genesis Bohuslavite is a secondary mineral, forming in the oxidation zone of polymetallic deposits, particularly uranium deposits. It forms as a result of the weathering of primary ore minerals in an environment rich in phosphorus and sulfur, under low pH (acidic) conditions. It originates in post-mining processes on the walls of old workings and on waste dumps. ## Mineral Associations At its type locality in Jáchymov, it co-occurs with gypsum, jarosite, goethite, quartz, hematite, and other rare phosphates and sulfates. ## Localities The most important and type locality for bohuslavite is the waste dump of the "Rovnost" uranium mine in Jáchymov, in the Karlovy Vary region of the Czech Republic. This is currently the only confirmed locality for this mineral worldwide.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, the quality of a specimen is primarily determined by the abundance and good development of crystalline aggregates visible under a microscope. Contrast with the substrate (rock matrix) and the presence of associated minerals can enhance the aesthetic and scientific value of the specimen. The most valuable samples come from the type locality. ## Popular Localities The only source of bohuslavite specimens is its type locality – Jáchymov in the Czech Republic.

Care and storage

## Cleaning Due to the extreme delicacy and microscopic size of the crystals, mechanical cleaning is impossible and inadvisable. Specimens should be protected from dust. ## What to Avoid Avoid contact with water and any chemicals. The mineral is likely unstable under varying humidity conditions and may dehydrate or dissolve. Protect it from vibrations and shocks. ## Storage Bohuslavite specimens should be stored exclusively in stable conditions, in closed, transparent "micromount" containers that protect them from physical damage, dust, and humidity changes.

Sources

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