Sabatierite

Chemical formula: Cu₆TlSe₄

Sabatierite is a rare copper-thallium selenide, forming tiny, metallic-lustered grains in association with other selenides.

## Characteristics Sabatierite is a rare mineral from the selenide group, chemically classified as a copper-thallium selenide. It occurs as very small, anhedral (irregularly shaped) grains, rarely exceeding 0.1 mm. It typically forms inclusions in other minerals, mainly berzelianite. It is opaque and has a metallic luster. Its color is steel-gray, often with a violet tint. ## Physical Properties The mineral is characterized by relatively low hardness, 2.5 on the Mohs scale, which means it can be scratched with a fingernail. It has a metallic luster and is opaque. Its streak is black. Due to the small size of the grains, precise determination of density is difficult and has not been accurately measured. ## Colors and Varieties Sabatierite occurs in a uniform, steel-gray color, which may exhibit a violet or pinkish-violet hue, particularly visible in reflected light under a microscope. No varieties have been distinguished. ## History and Name The mineral was discovered in 1976 and described by Z. Johan, P. Picot, F. Ruhlmann, and J. Kvaček. The name "sabatierite" was given in honor of Germain Sabatier (1853-1925), professor of mineralogy and crystallography at the University of Lille in France. The type locality (locus typicus) is the Bukov uranium mine in the Czech Republic. ## Uses Sabatierite has no industrial application due to its extreme rarity and microscopic size. It is of purely scientific interest and is an object of interest for specialized collectors of rare minerals.

Properties

Mohs hardness: 2.5
Luster: Metallic
Streak: Black
Density: 0
Transparency: Opaque
Crystal system: Orthorhombic

Diagnostic features

## Identification Identification of sabatierite under amateur conditions is practically impossible due to the microscopic size of the grains. It requires advanced laboratory techniques, such as microscopic analysis in reflected light (characteristic anisotropy and reflection colors) and chemical analysis (electron microprobe) to confirm the presence of copper, thallium, and selenium. ## Distinguishing from Similar Minerals It can be confused with other rare selenides with a metallic luster, such as bukovite, crookesite, or berzelianite, with which it often co-occurs. Definitive differentiation is possible only based on chemical composition analysis and crystallographic data. ## Crystal Forms Sabatierite forms exclusively anhedral, irregular grains and aggregates, usually less than 0.1 mm in size. No well-formed crystals have been observed.

Geological environment

## Genesis Sabatierite is a hydrothermal mineral. It forms at low to medium temperatures in calcite-selenide veins cutting metamorphic rocks, such as amphibolites. Its crystallization is associated with ore mineralization processes rich in selenium. ## Mineral Associations This mineral most often occurs in paragenesis with other selenides. Typical associated minerals include berzelianite (in which it often forms inclusions), bukovite, umangite, eukairite, crookesite, as well as uraninite, hematite, and calcite. ## Localities Sabatierite is an extremely rare mineral. Besides the type locality in the Bukov mine near Rožná in the Czech Republic, its occurrence has been confirmed in only a few other places worldwide, including the Tumiñico mine in Sierra de Cacho, Argentina, and the Předbořice area in the Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of sabatierite specimens is not assessed by typical aesthetic categories like color or crystal form, as it occurs as microscopic grains. The collector's value of a specimen depends primarily on the confirmed presence of the mineral (supported by analysis) and the richness of its association with other rare selenides on the same rock fragment. The richer the paragenesis, the more valuable the specimen is for a specialized collector. ## Popular Localities The most prized and historically important specimens come from the type locality – the Bukov mine in the Czech Republic. Material from this location serves as the standard for the mineral species.

Care and storage

## Cleaning Sabatierite specimens are usually microscopic and occur as inclusions in other minerals. They do not require and should not be subjected to mechanical or chemical cleaning to avoid damaging the delicate grains and the surrounding matrix. ## What to Avoid Avoid contact with chemicals, acids, and bases. Due to its low hardness, the mineral is very susceptible to scratches and mechanical damage. It should be protected from abrasion and impacts. ## Storage Specimens containing sabatierite should be stored in stable conditions, away from dust and moisture, preferably in sealed "micromount" boxes. Protect from direct contact with other, harder minerals.