Bounahasite

Chemical formula: Cu<sup>1+</sup>Cu<sup>2+</sup><sub>2</sub>(OH)<sub>3</sub>Cl<sub>2</sub>

Bounahasite is a very rare copper hydroxychloride, forming microscopic, tabular crystals of an intense green color.

## Characteristics Bounahasite is a secondary copper mineral, occurring as very small, hexagonal or pseudohexagonal crystals with a tabular habit. These crystals rarely exceed 0.2 mm and often form rosetted or radial aggregates. Due to its size, its visual features are most often observed under a microscope. ## Physical Properties Bounahasite crystals exhibit a vitreous luster. Hardness and density have not been precisely measured due to the small size and rarity of the material. It is a brittle mineral. ## Colors and Varieties This mineral is characterized by a vivid, emerald-green color. No varieties are known. ## History and Name Bounahasite was approved as a new mineral by the IMA in 2018 (IMA2018-058). Its name comes from its discovery locality - the Bounahas copper mine in the Moroccan province of Tata. It was described by an international team of researchers, including Polish mineralogists. ## Uses Bounahasite has no industrial application. It is of purely scientific and collectible significance, being a coveted item for specialized collectors of rare minerals.

Properties

Luster
Vitreous
Streak
Light green
Cleavage
Perfect on {0001}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Trigonal

Diagnostic features

## Identification Identifying bounahasite under amateur conditions is practically impossible. It requires advanced analytical methods, such as Raman spectroscopy or chemical analysis by electron microprobe (EDS/WDS). A visual feature, observed under high magnification, are the characteristic, hexagonal, tabular crystals of an emerald-green color, often in the form of rosettes. ## Distinguishing from Similar Minerals Bounahasite can be confused with other green secondary copper minerals, such as atacamite, paratacamite, claringbullite, or malachite. Differentiation is possible almost exclusively based on crystallographic and chemical analysis. The crystal shape is a key, though difficult to observe, clue. ## Crystal Forms Bounahasite forms thin, tabular crystals with a hexagonal or pseudohexagonal outline. These crystals often combine into rosetted, fan-shaped, or radial aggregates.

Geological environment

## Genesis Bounahasite is a secondary mineral, formed in the oxidation zone (gossan) of copper deposits, in an arid or semi-arid climate. It forms as a result of the alteration of primary copper sulfides under the influence of chloride-rich solutions. ## Mineral Associations This mineral co-occurs with other secondary copper minerals. At the type locality, it was found in association with atacamite, paratacamite, claringbullite, malachite, as well as goethite and quartz. ## Localities The only confirmed occurrence of bounahasite in the world is its type locality - the Bounahas copper mine, located in the Akka district, Tata province, Souss-Massa region in Morocco.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of bounahasite specimens is primarily assessed based on the richness and development of microcrystals on the matrix. Most valued are specimens with numerous, well-defined, rosetted aggregates of intense, emerald-green color. Contrast with the host rock is also important. Due to the microscopic nature of the mineral, the size of individual crystals is less important than the quality of the entire cluster. ## Popular Localities The only source of bounahasite specimens is the Bounahas mine in Morocco. Material from this locality is extremely rare and sought after by collectors specializing in mineral systematics and "micromounts."

Care and storage

## Cleaning Bounahasite specimens are extremely delicate and usually occur on a fragile matrix. Mechanical or chemical cleaning is not recommended. Any attempts at cleaning can irreversibly destroy the microscopic crystals. It is best to leave the specimen in the state in which it was found. ## What to Avoid Avoid contact with water, chemicals (especially acids), ultrasound, and sudden temperature changes. The crystals are very brittle and sensitive to shocks and touch. ## Storage It is recommended to store specimens only in specialized, sealed "micromount" boxes, which protect against dust, moisture, and mechanical damage. Avoid exposure to direct sunlight, which can affect the mineral's stability over time.

Sources

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