Hanauerite

Chemical formula: Ag₁+Hg₂+S₂-I₁-

Hanauerite is a very rare silver and mercury sulfide and iodide, forming microscopic, black crystals with a metallic luster.

## Characteristics Hanauerite is an extremely rare mineral from the sulfide group, which in its chemical composition combines silver, mercury, sulfur, and iodine. It was discovered and described only in 2020. It occurs as very fine, tabular or platy crystals, reaching sizes of up to approximately 100 micrometers. Its crystals are opaque and black in color. ## Physical Properties This mineral is characterized by a metallic luster and a black streak. Due to the microscopic size of the crystals, many of its physical properties, such as hardness or density, have not yet been precisely determined. The density calculated based on the chemical formula and unit cell parameters is approximately 7.19 g/cm³. ## Colors and Varieties Hanauerite is a mineral with a consistent, black coloration. No colored or commercial varieties are known. ## History and Name The mineral's name, Hanauerite, honors Richard Hanauer (born 1957), an Austrian mineral collector who found and provided the type material for research. The mineral was officially approved by the International Mineralogical Association (IMA) in 2020 (IMA2020-032). Its discoverers and authors of the description are H.-P. Bojar, F.P. Pfaﬀ, N.V. Chukanov, D.I. Belakovskiy, M. Lattner, and G.P. C. Cholopov. ## Uses Due to its extreme rarity and microscopic size, hanauerite has no practical application. It is solely an object of scientific interest and a valuable acquisition for specialized systematic collections.

Properties

Luster: Metallic
Streak: Black
Density: 7.19
Cleavage: Perfect on {100}
Transparency: Opaque
Crystal system: Orthorhombic

Diagnostic features

## Identification Identification of hanauerite is possible only through advanced laboratory methods, such as scanning electron microscopy with chemical analysis (EDS/WDS) and X-ray diffraction (XRD). Under collecting conditions, without specialized equipment, identification is impossible. Characteristic features include its chemical composition (Ag, Hg, S, I), black color, metallic luster, and co-occurrence with other rare mercury and silver minerals. ## Differentiation from Similar Minerals It can be confused with other fine, black minerals with a metallic luster, such as acanthite, cinnabar (metacinnabar variety), or other sulfides. Definitive differentiation requires chemical analysis, which will show the simultaneous presence of silver, mercury, sulfur, and iodine – a unique combination for hanauerite. ## Crystal Forms Hanauerite forms very small, thin, tabular or platy crystals, often grouped into small aggregates. These crystals do not exceed 100 micrometers in length and a few micrometers in thickness.

Geological environment

## Genesis Hanauerite forms as a result of low-temperature hydrothermal processes. It occurs in calcite-quartz veins cutting meta-volcanic rocks (specifically metarhyolites). Its formation is associated with the activity of solutions rich in silver, mercury, sulfur, and iodine. ## Mineral Associations This mineral occurs in association with other, often rare, minerals. In the type locality, its co-occurrence has been noted with calcite, quartz, cinnabar, native mercury, acanthite, pyrargyrite, miargyrite, polybasite, sphalerite, pyrite, chalcopyrite, galena, hematite, and undetermined minerals from the chlorine group and manganese oxides. ## Localities The only confirmed locality of hanauerite in the world is its type locality: the historical mines in the Rotfuchs area, near Weitental, municipality of Bruck an der Mur in Styria, Austria.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, the main criterion for value for collectors is the quality and richness of the host specimen. The most desirable samples are those on which well-formed, though tiny, hanauerite crystals, analytically identified, are visible. The aesthetics of the rock matrix and the presence of other rare associated minerals are also of great importance. Due to their size, specimens are evaluated under a microscope. ## Popular Localities The only source of hanauerite specimens is its type locality in Austria (Rotfuchs area, Bruck an der Mur, Styria). Material from this location is extremely difficult to obtain and represents a great rarity on the collector's market.

Care and storage

## Cleaning Due to their microscopic size and fragility, hanauerite specimens should not be cleaned mechanically or chemically. The safest method is to remove dust using compressed air from a safe distance. ## What to Avoid Avoid contact with any chemicals, acids, and detergents. It should not be subjected to ultrasound. Specimens should be protected from high temperatures and sudden temperature changes. As a mercury-containing mineral, situations leading to its pulverization and inhalation should be avoided. ## Storage Hanauerite specimens, usually found on a rock matrix, should be stored in stable conditions, in closed, padded "micromount" boxes to protect them from mechanical damage and dust. It is recommended to store them in a dry place, away from direct sunlight.

Sources

IMA Mineral List (CNMNC)