Sardashtite

Chemical formula: Ag₁+₉Cu₁+₂.₅Pb₂+₄₁Sb₃+₃₆.₅As₃+₇S₂-₁₁₂

Sardashtite is an extremely rare, metallic lead, antimony, silver, and copper sulfosalt, occurring as microscopic grains in Iran.

## Characteristics Sardashtite is a mineral known only in the form of microscopic, anhedral grains, not exceeding 100 micrometers in size. Observed in reflected light, it is grayish-white and opaque. Due to its microscopic nature, it does not form macroscopic specimens, and its identification is only possible using advanced analytical techniques. ## Physical Properties The mineral is characterized by a metallic luster. Its hardness has not been directly measured on the Mohs scale, but based on microhardness (VHN) measurements, it is estimated to be around 3.5-4. The density, calculated from its chemical composition and unit cell parameters, is 6.33 g/cm³. It is a brittle mineral. ## Colors and Varieties The only known color of sardashtite is grayish-white. No color varieties or commercial varieties are distinguished. ## History and Name Sardashtite was officially recognized as a new mineral species by the International Mineralogical Association (IMA) in 2020 (IMA2020-053). Its name comes from the city of Sardasht in West Azerbaijan Province, Iran, and was given in memory of the Kurdish victims of the chemical attack on that city in 1987. The type locality (place of discovery) is the Bavanat polymetallic deposit in Fars Province, Iran. ## Uses As a microscopic and extremely rare mineral, sardashtite has no commercial or industrial applications. Its significance is purely scientific and it is an object of interest for specialized micromineral collectors.

Properties

Mohs hardness: 3.5-4
Luster: Metallic
Streak: Black
Density: 6.33
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Amateur identification of sardashtite is impossible. Due to its microscopic size and visual similarity to many other sulfosalts, the only reliable method of identification is chemical analysis using an electron microprobe (EDS/WDS). A preliminary indication may be its occurrence in a specific mineral assemblage at the type locality. ## Distinguishing from Similar Minerals Sardashtite is visually indistinguishable from other gray, metallic minerals with which it co-occurs, such as galena, tennantite, or tetrahedrite. It differs from them by its unique chemical composition, containing lead, antimony, silver, copper, and arsenic simultaneously in specific proportions. ## Crystal Forms This mineral does not form well-developed crystals. It occurs exclusively as anhedral (irregular) grains, strongly intergrown with surrounding minerals.

Geological environment

## Genesis Sardashtite is a hydrothermal mineral. It formed as a primary component in low-temperature, polymetallic ore veins cutting through carbonate rocks (dolomites). ## Mineral Associations This mineral occurs in close association with other sulfides and sulfosalts. Most commonly these are: galena, tennantite-(Zn), wurtzite, tetrahedrite-(Fe), freibergite, and chalcopyrite. ## Localities The only confirmed locality of sardashtite in the world is its type locality - the Bavanat copper, silver, lead, and zinc deposit, in Fars Province, southern Iran.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of sardashtite specimens is assessed quite differently than for macroscopic minerals. Since it occurs as microscopic grains, the collectible value of a specimen depends on the abundance of sardashtite on the rock matrix and the presence of rare associated minerals. Analytically confirmed identification of the mineral is crucial. ## Popular Localities The only source of specimens is the Bavanat deposit in Iran. Material from this locality is extremely difficult to obtain and primarily goes to scientific institutions and highly specialized collections.

Care and storage

## Cleaning Specimens containing sardashtite, which are usually fragments of the host rock, should be cleaned with utmost care. It is recommended to use compressed air to remove dust. If necessary, a soft brush can be used. Avoid contact with water and chemicals. ## What to Avoid The mineral, as a sulfosalt, is potentially sensitive to moisture and oxidation. Contact with acids and other aggressive chemicals should be strictly avoided. It should not be heated or subjected to sudden temperature changes. ## Storage It is recommended to store specimens in a dry, stable environment, preferably in closed micromount boxes, which protect against dust and humidity changes.

Sources

IMA Mineral List (CNMNC)