Haydeeite

Chemical formula: Cu<sup>2+</sup><sub>3</sub>Mg(OH)<sub>6</sub>Cl<sub>2</sub>

Haydeeite is a very rare, turquoise-blue copper and magnesium mineral, discovered in 2007 in Chile.

## Characteristics Haydeeite is a hydrated copper and magnesium hydroxyl chloride, belonging to the atacamite group. It occurs as small, prismatic crystals up to 0.2 mm long, which often form radial or spherulitic aggregates. Its characteristic feature is an intense, turquoise-blue color. ## Physical Properties Haydeeite crystals exhibit a vitreous luster. The mineral is transparent to translucent. Due to the small size of the crystals, hardness and density have not been precisely measured, but are estimated based on minerals from the atacamite group. ## Colors and Varieties Haydeeite occurs in a uniform, turquoise-blue color. No color varieties or commercial names are known. ## History and Name The mineral was discovered in the Haydée (or Aida) mine in the Salar de Atacama province in Chile. Its name comes from the name of the mine where it was found. It was approved by the International Mineralogical Association (IMA) in 2007 under number IMA2007-017. The first scientific description was prepared by K. Schlüter, T. Malcherek, and G. D. Gatta in 2008. ## Uses Haydeeite has no industrial application. It is solely an object of interest for collectors specializing in rare minerals and micromounts.

Properties

Mohs hardness
3-4
Luster
Vitreous
Streak
Light blue
Density
3.25
Cleavage
Good on {1011}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Trigonal

Diagnostic features

## Identification Haydeeite can be identified by its characteristic turquoise-blue color, its form as small, prismatic crystals forming radial aggregates, and its co-occurrence with other secondary copper minerals in oxidation zones. ## Differentiation from Similar Minerals It can be confused with other blue and green secondary copper minerals, such as chrysocolla, atacamite, paratacamite, or clinoatacamite. Definitive differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS), due to visual similarity and co-occurrence. ## Crystal Forms It forms elongated, prismatic crystals, usually grouped into radial, acicular, or spherulitic (spherical) aggregates. Single, well-formed crystals are extremely rare.

Geological environment

## Genesis Haydeeite is a secondary mineral, forming in the oxidation zones (gossans) of copper ore deposits in extremely arid (desert) climatic conditions. It crystallizes from solutions rich in copper, magnesium, and chlorine. ## Mineral Associations It most commonly co-occurs with atacamite, paratacamite, clinoatacamite, anhydrite, gypsum, quartz, and halite. ## Localities The only confirmed locality of haydeeite in the world is its type locality – the Haydée (Aida) mine in the Salar de Atacama district, Antofagasta region, Chile.

Rarity

Extremely rare

For collectors

## Quality Criteria The most valuable specimens are those with rich, well-formed, radial crystal aggregates of an intense, turquoise-blue color, contrasting with the rock matrix. Due to the microscopic nature of the mineral, the richness and aesthetics of the aggregates visible under magnification are primarily evaluated. ## Popular Localities All known specimens come from a single location in the world – the Haydée mine in Chile, which makes this locality extremely important for collectors of systematic and rare minerals.

Care and storage

## Cleaning Haydeeite specimens should not be cleaned mechanically or chemically. Due to its fragility and rarity, it is best to leave any contaminants undisturbed. If dust removal is necessary, a gentle stream of compressed air can be used from a safe distance. ## What to Avoid Avoid contact with water, acids, ammonia, and other chemicals that may react with copper chlorides and hydroxides, leading to the destruction of the mineral. Also avoid ultrasound, high temperatures, and sudden temperature changes. ## Storage Haydeeite specimens, typically in the form of micromounts, should be stored in stable conditions, in closed "perky boxes" to protect them from dust, moisture, and mechanical damage. Avoid exposure to direct sunlight.

Sources

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