Auroselenide

Chemical formula: AuSe

Auroselenide is a rare gold selenide, occurring as tiny, metallic inclusions in other minerals.

## Characteristics Auroselenide is an extremely rare mineral from the selenide group. It forms microscopic, elongated or lamellar crystals, usually not exceeding a few tens of micrometers in size. It most often occurs as tiny inclusions in copper and lead selenides, which means its observation requires significant magnification. It is opaque and has a metallic luster. ## Physical Properties Due to the extreme rarity and microscopic size of its crystals, most physical properties of auroselenide have not been precisely determined. Hardness and density are unknown. The mineral is brittle. ## Colors and Varieties Observed in reflected light, it has a creamy-yellow color. No varieties have been distinguished. ## History and Name The name auroselenide directly refers to its chemical composition – gold (Latin: *aurum*) and selenium. It was described as a new mineral in 1972 by G.C. Jones, J.D.H. Nicholson, B.K. Sivamohanan, and D.C. Taylor based on material from a uranium mine in the Athabasca Lake region in Canada. ## Applications Due to its rarity and microscopic size, auroselenide has no industrial application and is solely an object of scientific and systematic interest.

Properties

Luster
Metallic
Transparency
Opaque
Crystal system
Tetragonal

Diagnostic features

## Identification Identification of auroselenide is possible only through advanced laboratory methods, such as ore microscopy in reflected light and chemical composition analysis (e.g., electron microprobe). Its characteristic features include a creamy-yellow color in reflected light and strong anisotropy. ## Distinguishing from similar minerals It can be confused with other microscopic selenides or sulfides with a metallic luster. It differs subtly in hue from native gold. Definitive distinction requires chemical analysis to confirm the presence of selenium. ## Crystal Forms Auroselenide forms small, lamellar or elongated crystals, as well as irregular grains intergrown with other minerals.

Geological environment

## Genesis Auroselenide forms under hydrothermal conditions, in metal selenide deposits, often associated with uranium mineralization. It forms at relatively low temperatures. ## Mineral Associations It co-occurs with other selenides, such as clausthalite, umangite, berzelianite, klockmannite, eucairite, as well as with uraninite and hematite. ## Localities Confirmed occurrences of auroselenide are few. Besides the type locality in the Athabasca Lake region in Saskatchewan, Canada, it has also been reported in the Tumiñico deposit in Sierra de Cacho, Argentina, and in the Předbořice uranium mine in the Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral, auroselenide is not collected for aesthetic purposes. Its collector's value pertains to the entire host rock specimen in which it has been identified. The most valuable samples are those with analytically confirmed presence of auroselenide, originating from the type locality or other rare occurrences, with rich associations of other selenides.

Care and storage

## Cleaning Specimens containing auroselenide should be cleaned with the utmost care, preferably using compressed air to remove dust. Contact with water and chemical agents should be avoided. ## What to avoid All chemicals, ultrasound, and sudden temperature changes should be avoided. As a brittle mineral, it is susceptible to mechanical damage. ## Storage Store in stable conditions, in a sealed container or display case, away from dust and moisture. Due to its microscopic nature, host rock specimens require proper labeling of the inclusion locations.

Sources

Read more