Klajite

Chemical formula: Mn₂+Cu₂+₄(As₅+O₄)₂(As₅+O₃OH)₂·₉H₂O

Klajite is a very rare, secondary copper and manganese arsenate, forming microscopic, tabular crystals of an intense blue color.

## Characteristics Klajite is a hydrated copper and manganese arsenate, occurring as very small, bladed or tabular crystals, which rarely exceed 0.2 mm. These crystals form rosette-like or radial aggregates, as well as thin coatings and crusts. Due to their microscopic size, visual features are difficult to observe without magnification. ## Physical Properties Klajite crystals exhibit an intense blue color and a vitreous luster. They are transparent and have a pale blue streak. The hardness on the Mohs scale is low, at 2, and the calculated density is 3.43 g/cm³. The mineral is brittle. ## Colors and Varieties Klajite occurs in a uniform, intense blue color. No varieties have been distinguished. ## History and Name The mineral's name honors František Klaj, a Czech mineral collector from western Bohemia, who found the first samples. Klajite was approved as a new mineral by the International Mineralogical Association (IMA) in 2014 (IMA2014-034). It was described by a team of mineralogists: Jiří Sejkora, Jakub Plášil, Radek Škoda, as well as Michal Ozdín and Josef Ježek. ## Uses Klajite has no industrial application. It is solely an object of scientific and collecting interest for specialists who collect rare minerals or specimens from specific localities (so-called "systematists").

Properties

Mohs hardness: 2
Luster: Vitreous
Streak: Pale blue
Density: 3.43
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Transparent
Crystal system: Triclinic

Diagnostic features

## Identification Identification of klajite is almost exclusively possible using advanced analytical methods, such as Raman spectroscopy or chemical analysis by electron microprobe (EDS/WDS). Preliminary identification in a collection is based on its intense blue color, characteristic form of microscopic, tabular crystals forming aggregates, and co-occurrence with other rare arsenates in known localities. ## Distinguishing from Similar Minerals Klajite can be confused with many other blue-colored secondary copper minerals, such as cyanotrichite, linarite, azurite, or geminite. "Eyeball" differentiation is practically impossible. The key is chemical analysis, which will show the presence of manganese and arsenic in specific proportions, and crystallographic analysis. ## Crystal Forms Klajite forms very small, thin, tabular or bladed crystals, often flattened. These crystals combine into characteristic, rosette-like or radial aggregates. It also occurs as thin crusts and coatings on the host rock.

Geological environment

## Genesis Klajite is a secondary mineral, formed in the oxidation (weathering) zones of polymetallic ore deposits rich in arsenic. It forms as a result of low-temperature hydrothermal processes in the presence of solutions rich in copper, manganese, and arsenic, which react with the surrounding rocks. ## Mineral Associations This mineral co-occurs with other rare arsenates and sulfates. In its type locality (Jáchymov), it was found in association with geminite, erythrite, annabergite, arsenolite, gypsum, and also unidentified minerals from the mickaelite group. ## Localities The only confirmed and described occurrence of klajite in the world is its type locality – the Svornost mine in Jáchymov (formerly St. Joachimsthal) in the Czech Republic, in the Ore Mountains (Krušné Hory) region.

Rarity

Very rare

For collectors

## Quality Criteria The quality of klajite specimens is primarily assessed based on the richness and aesthetics of the microscopic aggregates. Most valued are samples with clearly formed, radial or rosette-like clusters of intensely blue crystals, contrasting well with the host rock. Due to the microscopic nature of the mineral, the quality of the specimen under magnification is also crucial. ## Popular Localities The only source of klajite specimens is the Svornost mine in Jáchymov, Czech Republic. All samples available on the collector's market originate from this single, historic locality.

Care and storage

## Cleaning Klajite specimens should not be cleaned mechanically or chemically. Any attempts at cleaning can irreversibly damage the delicate, microscopic crystals. If dust removal is necessary, it can be done very carefully using a soft brush or a photographic air blower. ## What to Avoid Avoid contact with water, chemicals, and ultrasound. The mineral is brittle and sensitive to shocks and temperature changes. It should not be heated or exposed to direct sunlight. ## Storage Klajite specimens should be stored under stable conditions, in closed, padded "micromount" boxes to protect them from dust, mechanical damage, and sudden changes in humidity. It is best to keep them in a dry place, away from sources of light and heat.

Sources

IMA Mineral List (CNMNC)