Veselovskýite
Chemical formula: Zn²⁺Cu²⁺₄(As⁵⁺O₄)₂(As⁵⁺O₃OH)₂·9H₂O
Veselovskýite is a very rare, hydrated zinc and copper arsenate, forming characteristic blue-green, tabular crystals.
Properties
- Mohs hardness
- 2-3
- Color
- Colourless to greyish white (with a slight greenish tint)
- Luster
- Vitreous
- Streak
- Greyish white with a greenish tint
- Density
- 0
- Cleavage
- on {001}
- Fracture
- Irregular/Uneven
- Transparency
- Transparent,Translucent
- Crystal system
- Triclinic
Diagnostic features
## Identification Key diagnostic features include its characteristic blue-green color, tabular crystal habit, vitreous luster, and occurrence in the oxidation zones of polymetallic deposits. However, definitive identification requires advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS/WDS). ## Distinguishing from Similar Minerals It can be confused with other secondary copper arsenates of similar color, such as olivenite, euchroite, or cyanotrichite. Distinguishing it from these minerals based on visual characteristics is very difficult and often impossible without specialized equipment. The tabular crystal habit and co-occurrence with gypsum and zincosiderite can be helpful clues. ## Crystal Forms It forms thin, tabular or bladed crystals, elongated along the [100] axis and flattened parallel to {010}. These crystals often combine into radial, stellate, or disordered aggregates, and also form thin coatings on rock surfaces.
Geological environment
## Genesis Veselovskýite is a secondary mineral, forming in the oxidation (weathering) zones of polymetallic ore deposits. It forms as a result of reactions between arsenic-rich solutions, derived from the weathering of arsenopyrite and other sulfarsenides, and minerals containing copper and zinc. ## Mineral Associations In its type locality (Jáchymov), it co-occurs with gypsum, arsenolite, zincosiderite, krupkaite, lindackerite, native copper, sphalerite, tennantite-(Zn), and chalcopyrite. ## Localities It is an extremely rare mineral, known from only a few localities worldwide. The type locality is the Einigkeit (Svornost) Mine, in the Jáchymov (St. Joachimsthal) area in the Czech Republic. Its occurrence has also been confirmed in the Cap Garonne mine in Le Pradet, Var, France.
Rarity
Extremely rare
For collectors
## Quality Criteria The most highly prized specimens are those with well-formed, sharp crystals of intense, blue-green color, forming rich aggregates on a small rock matrix. Due to the microscopic size of the crystals, their abundance and aesthetic arrangement are key. Contrast with a light host rock also enhances the specimen's appeal. ## Popular Localities The only source of collectible specimens is the type locality – the Svornost mine in Jáchymov, Czech Republic. Specimens from this location, even microscopic ones, are highly sought after by specialized collectors of rare minerals (so-called "micromounters").
Care and storage
## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Any contact with water, and especially with chemicals, is highly inadvisable and can lead to damage or destruction of the delicate crystals. ## What to Avoid Contact with water, acids, detergents, and other cleaning agents must be absolutely avoided. The mineral is soft and brittle, so it must be protected from impacts and scratches. As a hydrated mineral, it can be sensitive to changes in temperature and humidity, which can lead to its dehydration and disintegration. ## Storage Veselovskýite specimens should be stored under stable conditions, in closed, airtight containers (e.g., "micromount boxes") that protect them from dust, mechanical damage, and humidity fluctuations. Avoid exposure to direct sunlight and high temperatures.