Perchiazziite

Chemical formula: Co²⁺₂(CO₃)(OH)₂

Perchiazziite is an extremely rare cobalt hydroxycarbonate, forming microscopic, pink, platy crystals.

## Characteristics Perchiazziite is a cobalt hydroxycarbonate that visually manifests as aggregates of very small, platy crystals. Individual crystals rarely exceed 50 micrometers, making them objects primarily for microscopic observation. They form pink aggregates, often in the form of rosettes or spherical clusters on the surface of the host rock. ## Physical Properties Due to the microscopic size of the crystals, most physical properties, such as hardness, density, or fracture, have not been precisely determined. The mineral's luster is described as pearly. It is a brittle mineral. ## Colors and Varieties Perchiazziite occurs in a characteristic pink color. No color varieties or commercial varieties are known. ## History and Name The mineral was named in honor of Professor Elena Perchiazzi (born 1957), an Italian mineralogist and crystallographer from the University of Pisa, in recognition of her contribution to mineralogy. It was approved by the International Mineralogical Association (IMA) in 2021 under number IMA2021-065. The discovery was made in the Castellaro mine in Liguria, Italy. ## Uses Perchiazziite has no industrial applications. Its significance is purely scientific and collectible, as an extremely rare and recently discovered mineral species.

Properties

Mohs hardness
4-0
Color
Orange-pink
Luster
Pearly
Streak
white
Density
3.970
Cleavage
Perfect on {0001}
Fracture
Irregular/Uneven
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of perchiazziite is impossible without advanced laboratory techniques, such as X-ray diffraction (XRD) or spectroscopy. In collector conditions, identification relies on a label from a reputable source. Visually, it can be suspected based on its pink color, pearly luster, and occurrence as small, platy crystals in association with other cobalt minerals. ## Distinguishing from Similar Minerals It can be confused with other secondary, pink cobalt minerals, such as sphaerocobaltite or erythrite. Sphaerocobaltite typically forms spheroidal aggregates or crusts, while erythrite forms characteristic acicular or radial aggregates. However, definitive differentiation requires chemical and structural analysis. ## Crystal Forms Perchiazziite crystallizes in the form of very small, thin, platy crystals with a hexagonal outline. These crystals often combine into rosette-like or spherical aggregates.

Geological environment

## Genesis It is a secondary mineral, forming in the oxidation (weathering) zones of cobalt-bearing ore deposits. It forms as a result of the action of carbonate-rich waters on primary cobalt minerals. ## Mineral Associations At the type locality (Castellaro mine), perchiazziite coexists with quartz, calcite, sphaerocobaltite, heterogenite, and unidentified minerals from the serpentine group. ## Localities The only confirmed occurrence of perchiazziite in the world is its type locality: Castellaro mine, Ne municipality, Graveglia Valley, Liguria, Italy.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of perchiazziite specimens is primarily assessed based on the richness and aesthetics of the microcrystal aggregates on the rock matrix. Specimens with clearly formed, intensely pink rosettes that contrast well with the substrate are most valued. Due to the microscopic nature of the mineral, the size of individual crystals is not a key criterion; rather, the overall area covered by the mineral is important. ## Popular Localities The only source of specimens is the Castellaro mine in Italy. Material from this locality is extremely rare and sought after by specialized collectors of rare minerals and "micromount" specimens.

Care and storage

## Cleaning Specimens should be handled with the utmost care. Due to the microscopic size and brittleness of the crystals, mechanical or chemical cleaning is not recommended. Any attempt at cleaning may irreversibly damage the specimen. Only very careful removal of loose dust using a photographic air blower is permissible. ## What to Avoid Contact with water, acids, detergents, and other chemicals must be strictly avoided. As a carbonate, the mineral is susceptible to reactions with acids. It should be protected from vibrations, impacts, and abrasion. ## Storage Perchiazziite specimens should be stored exclusively in specialized, sealed "micromount" boxes that protect them from dust, mechanical damage, and changes in humidity. They should not be exposed to direct sunlight.

External references

Sources

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