Shchurovskyite

Chemical formula: K₂CaCu₂+₆O₂(As₅+O₄)₄

Shchurovskyite is a very rare potassium, calcium, and copper arsenate, forming characteristic blue-green, tabular crystals.

## Characteristics Shchurovskyite is a mineral from the arsenate group, distinguished by its complex chemical composition and intense color. It occurs as very small, tabular or lath-like crystals, rarely exceeding 0.3 mm in length. These crystals often form radial or star-shaped aggregates, as well as rosettes and spherulites. Its characteristic, vivid blue-green color makes it recognizable despite its small size. ## Physical Properties Shchurovskyite crystals exhibit a vitreous luster. They are transparent to translucent. Due to the small size of the crystals, precise determination of hardness and density is difficult; the density calculated based on the formula and cell parameters is 4.41 g/cm³. ## Colors and Varieties This mineral occurs in a uniform, blue-green color. No varieties have been distinguished. ## History and Name Shchurovskyite was discovered in the dumps of the Arsenatnaya mine in the Tolbachik volcanic complex on Kamchatka, Russia. It was approved as a new mineral by the International Mineralogical Association (IMA) in 2013. Its name honors Grigory Efimovich Shchurovsky (1803–1884), a Russian geologist and paleontologist, professor and first rector of Moscow University, and founder of the Moscow Society of Naturalists. ## Uses Shchurovskyite has no industrial application. Its significance is purely scientific and collectible, as a very rare and recently discovered mineral.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: Light green
Density: 4.41
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Shchurovskyite can be identified by its characteristic blue-green color, vitreous luster, and typical forms of occurrence – small, tabular crystals forming radial or star-shaped aggregates. Occurrence in volcanic fumaroles is a key diagnostic clue. ## Distinguishing from Similar Minerals It can be confused with other secondary copper arsenates of similar color, such as lammerite, euchroite, or olivenite. Differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS), due to its unique chemical composition (presence of potassium and calcium). The morphology of aggregates (radial clusters of tablets) is also a helpful feature for visual identification. ## Crystal Forms Crystals are thin, tabular or lath-like, elongated along the [010] axis and flattened parallel to {001}. They typically form radial, star-shaped, or partially spherulitic aggregates, as well as irregular clusters.

Geological environment

## Genesis Shchurovskyite is a fumarolic mineral. It forms as a result of the sublimation of volcanic gases in exhalation zones, at temperatures of approximately 150-250°C. It crystallizes directly from gases rich in arsenic, copper, potassium, and calcium on the surface of volcanic rocks, such as basalt. ## Mineral Associations This mineral co-occurs with other rare arsenates and sulfates formed under similar conditions. The most common associated minerals include: tenorite, hematite, aphthitalite, langbeinite, arcanite, lammerite, johillerite, erykglaxite, badalovite, and urusovite. ## Localities The only confirmed locality for shchurovskyite in the world is its type locality – the Arsenatnaya fumarole, located on the second cinder cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption (1975-1976) on Kamchatka, Russia.

Rarity

Very rare

For collectors

## Quality Criteria The quality of shchurovskyite specimens is primarily assessed based on the richness and aesthetics of the crystal aggregates. The most prized specimens are those with well-formed, radial or star-shaped clusters of intense, blue-green color, clearly contrasting with the rock matrix. The size of the aggregates, although always microscopic, also affects the value – larger and more complete rosettes are more highly valued. ## Popular Localities The only source of specimens of this mineral is its type locality on the Tolbachik volcano in Kamchatka. All specimens available on the collector's market originate from this single, difficult-to-access locality.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Due to extreme delicacy and reactivity, contact with water and any chemical agents should be avoided. ## What to Avoid Contact with water, acids, bases, and other chemicals that can damage or dissolve the mineral must be strictly avoided. The crystals are very brittle and susceptible to mechanical damage. They should be protected from high temperatures and direct sunlight. ## Storage It is recommended to store specimens in tightly sealed, stable "micromount" containers to protect them from dust, moisture, and physical damage. Ideally, they should be kept in a dry place with a constant temperature.

Sources

IMA Mineral List (CNMNC)