Jasrouxite

Chemical formula: Ag₁+₁₆Pb₂+₄(Sb₃+₂₅As₃+₁₅)S₂-₇₂

Jasrouxite is an extremely rare silver, lead, antimony, and arsenic sulfosalt, known exclusively from the Jas Roux mine in France.

## Characteristics Jasrouxite is a mineral with a metallic luster and a gray color. It occurs as very small, anhedral grains, not exceeding 200 micrometers in size. These grains are usually intergrown with other sulfosalts, forming complex aggregates. Due to the microscopic size of its occurrences, its features cannot be observed with the naked eye. ## Physical Properties The mineral's hardness on the Mohs scale is 3.5. It is opaque, and its density, calculated based on its chemical composition and unit cell parameters, is 5.51 g/cm³. It has a black streak. ## Colors and Varieties The mineral has a uniform, gray color. No color varieties or commercial varieties are known. ## History and Name The name jasrouxite (previously known under the code IMA2007-038) comes from its discovery locality – the Jas Roux mine in the Hautes-Alpes department, France. It was officially recognized as a new mineral species by the International Mineralogical Association (IMA) in 2007, and its full scientific description was published a year later. The research team that described it was led by Yves Moëlo. ## Applications Jasrouxite has no industrial applications. Its significance is purely scientific, and it is an object of interest for specialized collectors of systematic minerals and micromounts.

Properties

Mohs hardness: 3.5
Luster: Metallic
Streak: Black
Density: 5.51
Cleavage: None
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of jasrouxite is impossible without advanced analytical techniques. Due to its occurrence as microscopic, anhedral grains, its recognition requires the use of an electron microscope with an EDS or WDS analyzer for precise determination of its chemical composition. Visual features do not allow it to be distinguished from other minerals. ## Distinguishing from Similar Minerals Jasrouxite coexists with numerous visually very similar silver, lead, and antimony sulfosalts, such as miargyrite, fizelyite, or andorite. Distinguishing it from these minerals is only possible based on chemical analysis. ## Crystal Forms This mineral does not form visible crystals. It occurs exclusively as anhedral (irregular) grains, strongly intergrown with surrounding minerals.

Geological environment

## Genesis Jasrouxite forms under low-temperature hydrothermal conditions, in polymetallic (Ag-Pb-Zn-Cu) veins associated with subvolcanic activity. ## Mineral Associations This mineral occurs in association with other, often rare, sulfosalts. It is most commonly accompanied by miargyrite, fizelyite, andorite IV, owensbyite, as well as more common ore minerals like pyrite, sphalerite, galena, chalcopyrite, and quartz. ## Localities The only confirmed locality of jasrouxite in the world is its type locality – the Jas Roux mine, located in the commune of La Chapelle-en-Valgaudémar in the Hautes-Alpes department, in the Provence-Alpes-Côte d'Azur region of France.

Rarity

Extremely rare

For collectors

## Quality Criteria In the case of jasrouxite, traditional quality assessment criteria such as color, clarity, or crystal form do not apply. The value of a specimen is purely scientific and depends on the richness of the mineral association and whether the presence of jasrouxite has been analytically confirmed. The most valuable samples are those containing the largest possible (on a micro scale) grains of the mineral in association with other rare sulfosalts from this locality. ## Popular Localities The only source of specimens is the Jas Roux mine in France, which is known among collectors specializing in rare sulfosalts and type minerals (discovered at a given locality).

Care and storage

## Cleaning Specimens containing jasrouxite should be cleaned with the utmost care, preferably using a soft brush to remove dust. Due to the microscopic nature of the grains, direct cleaning of the mineral itself is not possible. Avoid washing with water, and if absolutely necessary, use only distilled water and dry the specimen thoroughly immediately. ## What to Avoid As a sulfosalt, the mineral may be sensitive to chemicals, especially acids and strong detergents. It should be protected from prolonged exposure to intense light, high temperatures, and humidity, which can lead to its slow decomposition. ## Storage It is recommended to store specimens in closed, stable conditions, preferably in "micromount" boxes, which protect them from dust, mechanical damage, and sudden environmental changes.

Sources

IMA Mineral List (CNMNC)