Švenekite

Chemical formula: Ca(As<sup>5+</sup>O<sub>2</sub>(OH)<sub>2</sub>)<sub>2</sub>

Švenekite is a hydrated calcium arsenate, forming colorless, tabular crystals, discovered in the Czech Jáchymov mine.

## Characteristics Švenekite is a hydrated calcium arsenate. This mineral forms very small, colorless, transparent crystals with a tabular habit, reaching up to 0.2 mm in size. They usually occur as radial or randomly oriented aggregates and clusters. Due to the small size of the crystals, its visual features are difficult to observe without magnification. ## Physical Properties Švenekite crystals are characterized by a vitreous luster. They are transparent and colorless. The Mohs hardness is estimated to be around 2-3, and the density calculated from the formula and cell parameters is 3.11 g/cm³. The mineral does not exhibit fluorescence under ultraviolet light. ## History and Name The mineral is named in honor of the Czech mineralogist and crystallographer, František Švenek (1930-2009), in recognition of his contributions to the mineralogy of Jáchymov. Švenekite was approved as a new mineral by the International Mineralogical Association (IMA) in 2006 (IMA2006-039). It was first described in 2008 by Jakub Plášil and co-workers based on specimens found in the Svornost mine in Jáchymov, Czech Republic.

Properties

Mohs hardness
2-3
Luster
Vitreous
Streak
White
Density
3.11
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Transparent
Crystal system
Triclinic

Diagnostic features

## Identification Identification of švenekite is possible almost exclusively through advanced analytical methods, such as X-ray diffraction (XRD) and chemical spectroscopy (EDS/WDS). For collectors, identification relies on knowledge of the location (Jáchymov) and associated minerals. Visually, it is a colorless mineral forming small, tabular crystals in radial aggregates. ## Distinguishing from similar minerals It can be confused with other secondary arsenates, such as pharmacolite, haidingerite, or picropharmacolite, which can also be colorless and occur in similar environments. However, pharmacolite and haidingerite typically form acicular or bladed crystals in fibrous or crustal aggregates. Definitive differentiation requires laboratory analysis. ## Crystal forms Švenekite crystallizes as thin, tabular crystals, flattened parallel to the {010} plane. These crystals combine into radial or irregular aggregates on the surface of the host rock.

Geological environment

## Genesis Švenekite is a secondary mineral, forming in the oxidation zone of arsenic-bearing ore deposits. It forms as a result of the weathering of primary arsenic minerals, such as native arsenic, in the presence of calcium-rich solutions. ## Mineral associations This mineral occurs in association with other secondary arsenates. At the type locality (Jáchymov), it was found in association with native arsenic, pharmacolite, haidingerite, picropharmacolite, gypsum, and arsentsumebite. ## Localities The only confirmed occurrence of švenekite in the world is its type locality: the Geister vein in the Svornost mine, in the Jáchymov (St. Joachimsthal) district, Karlovy Vary Region, Czech Republic.

Rarity

Extremely rare

For collectors

## Quality criteria As a "micromount" type mineral, the quality of a specimen is primarily determined by the richness and sharpness of the developed crystals in the aggregate, as well as their transparency. The aesthetics of the composition with associated minerals is also important, especially if švenekite grows on a contrasting substrate. Due to its extreme rarity, every well-documented specimen is valuable. ## Popular localities The only source of specimens is the Svornost mine in Jáchymov (Czech Republic), making it highly sought after by collectors specializing in rare minerals and those from specific localities.

Care and storage

## Cleaning Due to its extreme rarity, small crystal size, and fragility, mechanical cleaning is not recommended. If absolutely necessary, compressed air (from a safe distance) can be used to remove dust. Avoid contact with water and any chemicals. ## What to avoid As an arsenate, the mineral is potentially toxic and should be handled with care, avoiding dust inhalation and washing hands after contact. Avoid all acids and detergents. The crystals are very brittle and susceptible to mechanical damage. ## Storage Švenekite specimens should be stored exclusively in specialized, sealed "micromount" containers to protect them from damage, dust, and moisture. They should be kept away from sources of vibration and direct sunlight.

Sources

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