Cuprocherokeeite

Chemical formula: [Pb₂+₈Zn₂+₃Cu₂+(OH)₁₆](S₆+O₄)₄·₄H₂O

Cuprorcherite is an extremely rare, secondary zinc, lead, and copper sulfate mineral, forming microscopic, platy crystals of a blue color.

## Characteristics Cuprorcherite is a hydrated lead, zinc, and copper sulfate. It occurs as extremely small, platy or bladed crystals, which rarely exceed 50 micrometers in length. These crystals form rosette-like or radial aggregates, as well as thin coatings and crusts on the surface of the host rock. Due to the microscopic size of the crystals, visual features are difficult to observe without specialized equipment. ## Physical Properties Cuprorcherite crystals exhibit a vitreous luster. Hardness and density have not been precisely measured due to the small size and rarity of the material. The mineral is brittle. ## Colors and Varieties This mineral is characterized by a light blue to blue-green color. The streak is very light blue. No varieties have been distinguished. ## History and Name Cuprorcherite was discovered in the Cherokee Mine in Lincoln County, Georgia (USA) and described in 2022 by a team of mineralogists led by Stuart J. Mills. The name refers to the type locality (Cherokee Mine) and the presence of copper (Latin: *cuprum*) in its chemical composition, distinguishing it from the similar mineral cherokeeite. ## Uses Cuprorcherite has no industrial application. It is solely an object of scientific and collecting interest for specialists gathering rare minerals and microminerals.

Properties

Luster: Vitreous
Streak: Very pale blue
Cleavage: Perfect on {0001}
Fracture: Brittle
Transparency: Transparent
Crystal system: Trigonal

Diagnostic features

## Identification Identification of cuprorcherite is possible only through advanced analytical methods, such as Raman spectroscopy, X-ray diffraction (XRD), and chemical analysis (EDS/WDS). Under collecting conditions, identification relies on label analysis and comparison with the appearance of specimens from the type locality. Characteristic features include microscopic, light blue, platy crystals forming rosette-like aggregates. ## Distinguishing from Similar Minerals Cuprorcherite is visually almost identical to cherokeeite, from which it differs by the presence of copper in its structure. It can also be confused with other secondary copper and zinc minerals of blue color, such as ktenasite, serpierite, or linarite. Definitive distinction from these minerals requires specialized laboratory tests. ## Crystal Forms Cuprorcherite crystallizes in the form of very small, thin, platy crystals with a hexagonal or rhombic outline. These crystals often combine into radial or rosette-like aggregates, and also form thin crusts and coatings.

Geological environment

## Genesis Cuprorcherite is a secondary mineral that forms in the oxidation zones (gossans) of polymetallic ore deposits. It originates from the weathering of primary sulfides, such as galena, sphalerite, and chalcopyrite, in the presence of sulfate-rich waters. Its formation is associated with a low pH environment. ## Mineral Associations At the type locality (Cherokee Mine, Georgia, USA), cuprorcherite is associated with anglesite, cherokeeite, linarite, brochantite, hemimorphite, goethite, and quartz. ## Localities The only confirmed and described locality of cuprorcherite occurrence in the world is its discovery site – the Cherokee Mine, located in Lincoln County, Georgia, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of cuprorcherite specimens is primarily assessed based on the richness and aesthetics of the microscopic crystalline aggregates. The most valued specimens are those with clearly formed, rosette-like clusters of intense, blue color, contrasting well with the rock matrix. Crystal size, although always microscopic, is also important – larger and better-formed crystals are more desirable. The presence of associated minerals, which can enhance the visual appeal of the specimen, is also significant. ## Popular Localities The only source of collector specimens is the type locality – the Cherokee Mine in Georgia, USA. Specimens from this location are highly sought after by collectors specializing in rare minerals and microminerals.

Care and storage

## Cleaning Cuprorcherite specimens are extremely delicate and usually microscopic in size. Mechanical or chemical cleaning is not recommended. Any attempts at cleaning may irreversibly destroy the crystalline aggregates. If dust removal is necessary, it can be done very carefully using a photographic air blower, without touching the mineral surface. ## What to Avoid Contact with water, acids, bases, and any solvents must be strictly avoided. The mineral is likely soluble in acids. It should be protected from vibrations, impacts, and abrasion. It should not be heated or exposed to temperature changes. ## Storage Specimens should be stored exclusively in specialized "micromount" boxes, which protect them from mechanical damage and dust. Store in a dry place with stable temperature, away from direct sunlight.

Sources

IMA Mineral List (CNMNC)