Bukovskýite

Chemical formula: Fe³⁺₂(As⁵⁺O₄)(S⁶⁺O₄)(OH)·₇H₂O

Bukovskýite is a rare, hydrated iron arsenate-sulfate, forming earthy or reniform aggregates with a characteristic pale greenish color.

## Characteristics Bukovskýite is a secondary mineral of iron, arsenic, and sulfur, occurring in the oxidation zones of ore deposits. It forms characteristic aggregates ranging from earthy and powdery to massive, reniform, or spherical. Its structure is typically very fine-grained, which gives it a dull, earthy appearance. Single, well-formed crystals are rarely observed, and specimens most often take the form of coatings and crusts on other minerals. ## Physical Properties This mineral is relatively soft, with a Mohs hardness of approximately 2. It has a low density of 2.33 g/cm³. It is opaque, and its luster is described as earthy or dull. Due to its porous, earthy nature, it is brittle and easily crumbled. ## Colors and Varieties Bukovskýite occurs in shades from pale yellowish-green to grayish-green. Its color is quite characteristic, although it can be confused with other secondary arsenic minerals. No named color varieties or commercial varieties are distinguished. ## History and Name The mineral's name honors the Czech chemist Antonín Bukovský (1865-1950), who first studied and described this substance in 1914 from the dumps of old silver mines in Kaňk near Kutná Hora, Czech Republic. It was formally recognized and described as a distinct mineral species by František Novák in 1967, with the type locality confirmed in the same historical location. ## Uses Bukovskýite has no industrial applications. Its significance is limited to the scientific and collecting spheres, as a rare and interesting secondary mineral.

Properties

Mohs hardness: 5
Luster: Earthy
Streak: Yellowish-white
Density: 2.334
Cleavage: Indiscernible
Fracture: Earthy
Transparency: Opaque
Crystal system: Triclinic

Diagnostic features

## Identification Bukovskýite is most easily recognized by its characteristic mode of occurrence – earthy, powdery, or reniform aggregates of a pale greenish color. It occurs in paragenesis with other arsenates in oxidation zones of deposits. Its low hardness and reaction to moisture are also helpful features. ## Distinguishing from Similar Minerals It can be confused with other secondary iron arsenates, such as pitticite, which often has a similar form and color but is amorphous. Scorodite can also be similar, but it usually forms better-developed crystals and has a vitreous luster. Definitive differentiation requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms Bukovskýite crystals are extremely rare and microscopic in size. It typically forms massive, earthy, powdery, reniform, or botryoidal aggregates, as well as crusts and coatings.

Geological environment

## Genesis Bukovskýite is a secondary mineral, formed as a result of weathering (oxidation) of ore minerals rich in arsenic, mainly arsenopyrite, in the presence of sulfide minerals such as pyrite. It forms under conditions of low temperature and pH, most often in old mine dumps or in the oxidation zones of polymetallic deposits. ## Mineral Associations This mineral often co-occurs with other oxidation products. Its most common associations include: arsenopyrite (as a primary mineral), pitticite, jarosite, scorodite, gypsum, and limonite (goethite). ## Localities The most important and historical locality for bukovskýite is its type locality – Kaňk near Kutná Hora in the Czech Republic. It is also known from several other places worldwide where similar geochemical conditions existed, including the Lavrion mines in Greece and some localities in Germany (e.g., in Saxony).

Rarity

Rare

For collectors

## Quality Criteria Specimens with well-formed, rich reniform or botryoidal aggregates of an intense, greenish color are most valued by collectors. An aesthetic rock matrix and the presence of associated minerals that highlight the paragenesis are also important. Due to its rarity, even small but well-defined specimens are valuable. ## Popular Localities By far the most classic and sought-after specimens come from the type locality in Kaňk, Czech Republic. These serve as the standard for this mineral and are most highly prized in the collector's market.

Care and storage

## Cleaning Bukovskýite specimens are very delicate and sensitive to water. Wet cleaning should be avoided, as it can lead to dissolution or damage to the mineral. To remove dust, a very soft brush can be used, or dust can be carefully blown off with compressed air from a distance. ## What to Avoid Contact with water, acids, and other chemicals must be absolutely avoided. The mineral is sensitive to changes in humidity and temperature. It should not be heated or exposed to direct sunlight, which can cause dehydration and structural changes. ## Storage It is recommended to store specimens in a dry, stable environment. They should ideally be placed in a closed, airtight box (e.g., a "membrane box" or a box with cotton) to protect them from mechanical damage, dust, and humidity fluctuations.