Zincobradaczekite
Chemical formula: NaCu²⁺Cu²⁺Zn²⁺₂(AsO₄)₃
Dark green sodium, copper, and zinc arsenate, forming spherical aggregates of tiny, platy crystals.
Properties
- Color
- Blue, greenish-blue, grey-blue or bluish-grey
- Luster
- Vitreous
- Streak
- Pale green
- Density
- 4.71
- Cleavage
- Perfect on {010}
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of zincobradaczekite is possible almost exclusively using advanced analytical methods, such as Raman spectroscopy or chemical analysis with an electron microprobe (EDS/WDS). Visually, it is characterized by its dark green color and occurrence as small, spherical aggregates. ## Distinguishing from Similar Minerals It can be confused with other green secondary copper and zinc minerals, such as conicalcite, zincolivenite, or sometimes malachite. Definitive distinction requires specialized analytical equipment. Co-occurrence with other rare arsenates in a specific environment is an important diagnostic clue. ## Crystal Forms It forms spherical or hemispherical aggregates composed of very small, elongated, platy crystals. Single, well-formed crystals are extremely rare and microscopic in size.
Geological environment
## Genesis Zincobradaczekite is a secondary mineral that formed as a result of weathering (oxidation) processes of primary arsenical ores in a copper and zinc-rich environment. Its occurrence is associated with the dumps of former mines, where specific chemical conditions favor the crystallization of rare arsenates. ## Mineral Associations This mineral occurs in association with other rare arsenates, such as conicalcite, cuproadamin, strashimirit, lavendulan, as well as gypsum and quartz. ## Localities The only confirmed occurrence (type locality) of zincobradaczekite in the world is the dumps of the former Maria-Josefa mine, near Esslingen, in the municipality of Weiz, Styria, Austria.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of zincobradaczekite specimens is primarily assessed based on the richness and definition of spherical aggregates on the rock matrix. Most valued are specimens with numerous, well-formed, intensely green spherules, clearly contrasting with the substrate. The size of the aggregates, although always microscopic, is also important – larger spherules are more desirable. The aesthetics of the overall composition and the presence of contrasting associated minerals are also significant. ## Popular Localities The only source of specimens is the type locality – the dumps of the Maria-Josefa mine in Austria. All specimens available on the collector's market originate from this single location.
Care and storage
## Cleaning Specimens should be handled with utmost care. Cleaning is not recommended due to the fragility and microscopic size of the crystals. If necessary, compressed air can be used from a safe distance to remove loose dust particles. ## What to Avoid Avoid contact with water, chemicals, and especially acids, which can damage the mineral. Ultrasonic cleaning is also not advisable. Specimens are sensitive to shocks and abrasions. ## Storage It is recommended to store specimens exclusively in specialized "micromount" boxes, which protect them from mechanical damage, dust, and moisture. Avoid exposure to direct sunlight and sudden temperature changes.