Yancowinnaite

Chemical formula: Pb²⁺Cu²⁺Al(As⁵⁺O₄)₂OH·H₂O

Yancowinnaite is a very rare, secondary lead, copper, and aluminum arsenate, forming blue-green, rosette-like crystal aggregates.

## Characteristics Yancowinnaite is a very rare secondary mineral from the arsenate group, chemically classified as a hydrated lead, copper, and aluminum arsenate. It occurs as small, bladed or tabular crystals, which most often form spherical or hemispherical aggregates with a radial internal structure, resembling rosettes. Individual crystals rarely exceed 1 mm in length. Due to its rarity and small crystal size, it is a mineral of primarily scientific and collector interest. ## Physical Properties Yancowinnaite crystals exhibit a vitreous luster. The mineral is translucent. Its Mohs hardness is approximately 3, and its density has been calculated at 4.61 g/cm³. It is a brittle mineral. ## Colors and Varieties Yancowinnaite is characterized by an attractive, blue-green color. No varieties have been distinguished. ## History and Name The mineral was discovered in the dumps of the Kintore Opencut mine in Broken Hill, Yancowinna County, New South Wales (Australia). Its name, approved by the IMA in 2007, comes directly from the name of the county where its type locality is situated. It was described by a team of mineralogists: Peter Elliott, Gerald Giester, Uwe Kolitsch, and Allan Pringle. ## Uses Yancowinnaite has no industrial application. It is exclusively an object of interest for specialized collectors of rare minerals and scientists.

Properties

Mohs hardness
3
Color
Yellowish-green to green
Luster
Vitreous
Streak
Yellow
Density
5.31
Cleavage
One perfect cleavage
Fracture
Irregular/Uneven
Transparency
Translucent
Crystal system
Triclinic

Diagnostic features

## Identification Yancowinnaite can be identified by its characteristic blue-green color and typical occurrence in the form of radial, spherical aggregates composed of small, bladed crystals. Its occurrence in the oxidation zones of polymetallic deposits, in association with other secondary arsenates, is also an important clue. ## Distinguishing from Similar Minerals It can be confused with other secondary copper minerals of similar color and form, such as agardite, olivenite, or cyanotrichite. Differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS), due to the presence of lead and aluminum in yancowinnaite's composition. ## Crystal Forms It forms elongated, bladed crystals with a rhombic cross-section, terminating acutely. These crystals almost always occur in radial, spherical or hemispherical aggregates and rosettes.

Geological environment

## Genesis Yancowinnaite is a secondary mineral, forming in the oxidation (weathering) zones of polymetallic ore deposits rich in arsenic, lead, and copper. It forms as a result of reactions of solutions percolating through rocks containing primary sulfides and arsenides. ## Mineral Associations At the type locality (Broken Hill, Australia), it co-occurs with minerals such as quartz, mimetite, segnitite, beudantite, agardite-(Y), olivenite, libethenite, cyanotrichite, brochantite, malachite, azurite, cerussite, and anglesite. ## Localities Yancowinnaite is an extremely rare mineral. Besides the type locality in Broken Hill, Australia, its occurrence has only been confirmed in the Clara mine in the Black Forest (Germany).

Rarity

Extremely rare

For collectors

## Quality Criteria The most valued specimens are those with well-formed, spherical aggregates of intense, blue-green color, contrasting with the rock matrix (most often quartz). The size of the aggregates and their completeness are key factors influencing value. Due to the microscopic size of the crystals, specimens are primarily evaluated under magnification. ## Popular Localities The only source of collector specimens is its type locality – the Kintore Opencut mine in Broken Hill, New South Wales, Australia. Specimens from the Clara mine in Germany are even rarer.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using a soft brush to remove dust. Due to its brittleness and potential reactivity, contact with water and any chemical agents should be avoided. ## What to Avoid Absolutely avoid washing in water, ultrasonic cleaning, and exposure to chemicals, including acids and bases. The mineral is brittle and sensitive to mechanical damage. It should be protected from high temperatures and sudden changes in temperature. ## Storage It is recommended to store specimens in stable conditions, in closed, padded "micromount" boxes, to protect them from dust, moisture, and physical damage. Avoid exposure to direct sunlight.

External references

Sources

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