Spiridonovite

Chemical formula: (Cu₁+₁-xAg₁+x)₂Te₂-, (x≈₀.₄)

Spiridonovite is a very rare copper silver telluride, forming tiny, metallic inclusions in other ore minerals.

## Characteristics Spiridonovite is a very rare mineral from the sulfide group, specifically a copper silver telluride. It occurs as very small, irregular grains or inclusions in other minerals, mainly bornite. Its size rarely exceeds 100 micrometers. It usually forms aggregates with other tellurides. It is opaque and has a metallic appearance. ## Physical Properties This mineral is characterized by a metallic luster. Due to the microscopic size of its crystals, precise determination of hardness and other physical properties is very difficult. Neither cleavage nor fracture has been observed. ## Colors and Varieties Spiridonovite is gray to purplish-gray, often with a pinkish hue. In reflected light under a microscope, its color is described as creamy-pink or purplish. No varieties are distinguished. ## History and Name The mineral was named in honor of Ernst Maksimovich Spiridonov (born 1938), a Russian mineralogist and researcher from Moscow University, in recognition of his contribution to the study of tellurides. It was discovered and described in 1999. ## Uses Spiridonovite has no industrial application. It is of purely scientific significance and is an object of interest for specialized collectors of rare minerals.

Properties

Luster: Metallic
Cleavage: None
Transparency: Opaque
Crystal system: Trigonal

Diagnostic features

## Identification Identification of spiridonovite is only possible using advanced laboratory techniques, such as reflected light ore microscopy and chemical analysis using an electron microprobe (EDS/WDS). Its characteristic creamy-pink color in reflected light and chemical composition are crucial for identification. ## Differentiation from Similar Minerals It can be confused with other microscopic silver and copper tellurides, such as weissite (Cu₂Te) or rickardite (Cu₇Te₅). Differentiation requires precise analysis of the copper to silver and tellurium ratio. ## Crystal Forms Spiridonovite occurs as anhedral (irregular) grains and aggregates, usually ranging from 5 to 100 micrometers in size. It forms inclusions and rims around other minerals, often in complex intergrowths with other tellurides.

Geological environment

## Genesis It is a hydrothermal mineral, crystallizing in the final stages of mineralization processes in ore veins. It forms under low-temperature conditions, below 93°C, in an environment rich in tellurium and copper. ## Mineral Associations It most commonly co-occurs with bornite, in which it forms inclusions. It is also accompanied by other tellurides, such as weissite, rickardite, sylvanite, altaite, as well as native gold, chalcocite, digenite, and covellite. ## Localities The most important and only confirmed occurrences of this mineral are the Kommunar mine in the Khakassia region (Russia) and the Ozernovskoe deposit in Kamchatka (Russia).

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a spiridonovite specimen depends solely on the confirmation of its presence by analytical methods. Since it occurs as microscopic grains, aesthetic values are not applicable. The most valuable samples are those with accurately studied and documented presence of the mineral, originating from the type locality. ## Popular Localities The only source of collector material is the Kommunar mine in Russia.

Care and storage

## Cleaning Specimens containing spiridonovite, due to its microscopic nature and occurrence as inclusions, are generally not cleaned. Any mechanical or chemical intervention can destroy the delicate mineral grains. If necessary, compressed air can be used to remove dust. ## What to Avoid Avoid contact with any chemicals, acids, and cleaning agents. Ultrasonic cleaning is not recommended. Specimens should be protected from moisture and sudden temperature changes. ## Storage Specimens containing spiridonovite are best stored under stable conditions, in closed "micromount" boxes, protecting them from dust, moisture, and mechanical damage.

Sources

IMA Mineral List (CNMNC)