Yvonite

Chemical formula: Cu₂+(As₅+O₃OH)·₂H₂O

Yvonite is a rare, secondary copper arsenate with a characteristic blue-green color, forming small, bladed crystals.

## Characteristics Yvonite is a hydrated copper arsenate that visually presents as aggregates of small, bladed or tabular crystals. It typically forms small aggregates and coatings. Its most characteristic feature is its intense, blue-green color. ## Physical Properties Yvonite crystals exhibit a vitreous luster. This mineral is transparent to translucent. Due to the small size of the crystals, its physical properties, such as hardness or density, are difficult to measure precisely on individual specimens. ## Colors and Varieties The dominant and only known color of yvonite is a vivid, blue-green. No color or commercial varieties have been distinguished. ## History and Name The mineral is named in honor of Dr. Klaus Yvon (born 1943), professor of crystallography at the University of Geneva, Switzerland, in recognition of his contributions to this field of science. Yvonite was first described in 1998 by Halil Sarp and Pierre Perroud. ## Uses Yvonite has no industrial application. Its significance is purely scientific and collectible, being an object of interest for specialized collectors of rare minerals.

Properties

Mohs hardness: 3-4
Luster: Vitreous
Streak: Pale green
Density: 3.45
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent to Translucent
Crystal system: Triclinic

Diagnostic features

## Identification Characteristic features of yvonite include its intense blue-green color, the form of small, bladed crystals, and its occurrence in paragenesis with other secondary copper arsenates. However, definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from similar minerals Yvonite can be confused with other secondary, green and blue copper arsenates, such as geminite, olivenite, euchroite, or cornwallite. Distinguishing it based on visual characteristics is extremely difficult and often impossible without specialized equipment. Key factors are the study of crystal habit and associated minerals at a given locality. ## Crystal Forms Yvonite crystallizes in the form of very small, elongated, bladed crystals, often flattened. It forms rosette-like aggregates, coatings, or occurs as single, dispersed crystals on the host rock.

Geological environment

## Genesis Yvonite is a secondary mineral, forming in the oxidation (weathering) zones of copper and arsenic ore deposits. It forms as a result of surface water action on primary minerals containing these elements. ## Mineral Associations This mineral co-occurs with other rare, secondary arsenates. At the type locality (Salsigne, France), it was found in association with geminite, lindackerite, picropharmacolite, pharmacolite, native arsenic, realgar, and orpiment. ## Localities The most important and type locality for yvonite is the Salsigne gold mine, near Carcassonne in France. This is the only confirmed and well-documented locality for this mineral worldwide.

Rarity

Very rare

For collectors

## Quality Criteria For collectors, the intensity and uniformity of the blue-green color are most important. Specimens with well-formed, distinct crystals, forming rich, rosette-like aggregates on a contrasting rock matrix, are highly valued. Due to its rarity, any specimen from a confirmed locality is valuable. ## Popular Localities The only source of collector specimens is the Salsigne mine in France. Material from this location is considered classic and most desirable.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using compressed air to remove dust. Due to its fragility and potential reactivity, contact with water and any chemical agents should be avoided. ## What to avoid Ultrasonic cleaners, steam cleaning, acids, and all solvents must be absolutely avoided. The mineral is sensitive to high temperatures and humidity. As an arsenate, it is toxic – avoid inhaling dust and wash hands after each contact. ## Storage Storage in stable conditions, in a dry environment, away from direct sunlight and heat sources, is recommended. It is best kept in a closed, transparent collector's box, which protects against mechanical damage and dust.

Sources

IMA Mineral List (CNMNC)