Bilibinskite
Chemical formula: PbAu<sub>3</sub>Cu<sub>2</sub>Te<sub>2</sub>
Bilibinskite is a rare, metallic mineral of lead, gold, copper, and tellurium, forming microscopic grains in gold deposits.
Properties
- Mohs hardness
- 4.5-5
- Luster
- Metallic
- Density
- 14.26
- Cleavage
- None
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Cubic
Diagnostic features
## Identification Identification of bilibinskite is possible only through advanced laboratory techniques. In the field and in a collection, it is visually unrecognizable. The primary method is chemical composition analysis using an electron microprobe (EDS/WDS) on a polished section. Its optical properties in reflected light (color, anisotropy) are auxiliary but insufficient for definitive identification. ## Distinguishing from Similar Minerals Bilibinskite is almost visually identical to other rare gold tellurides, such as bogdanovite, bezsmertnovite, or nagyagite, with which it often co-occurs. Differentiation requires precise chemical analysis to determine the exact proportions of gold, copper, lead, and tellurium. ## Crystal Forms This mineral does not form well-developed crystals. It occurs exclusively as anhedral (irregular) grains and aggregates, often forming rims around other minerals, especially native gold.
Geological environment
## Genesis Bilibinskite is a hydrothermal mineral. It forms in the final stages of crystallization of volcanogenic gold and tellurium deposits, in quartz veins cutting volcanic rocks such as andesites and rhyolites. ## Mineral Associations It most commonly co-occurs with native gold, which it often encloses. It is also accompanied by other tellurides, such as bogdanovite, bezsmertnovite, kotschubeite, sylvanite, petzite, hessite, as well as pyrite, chalcopyrite, and quartz. ## Localities The most important and well-documented bilibinskite localities worldwide include: - Aginskoye deposit in Kamchatka, Russia (type locality). - Pionerskoye Mine, Amur region, Russia. - Campbell Mine, Bisbee, Cochise County, Arizona, USA. - El Indio Mine, Elqui Province, Chile.
Rarity
Very rare
For collectors
## Quality Criteria As a microscopic mineral, bilibinskite is not evaluated by typical criteria such as size or crystal form. The value of a specimen lies in the richness of the paragenesis – the more rare tellurides accompanying bilibinskite on a single sample, the more valuable it is. Certainty of identification, confirmed by chemical analysis, is also key. Specimens from the type locality (Aginskoye) are particularly prized by specialized collectors. ## Popular Localities The most sought-after specimens come from the Aginskoye deposit in Kamchatka, Russia. Material from the Campbell Mine in Arizona (USA) and El Indio in Chile is also sometimes available on the specialized market.
Care and storage
## Cleaning Specimens containing bilibinskite, due to the microscopic nature of the grains and their embedding in the rock matrix, generally do not require and should not be mechanically cleaned. Any attempts at cleaning may damage or remove the fine mineral grains. If dust removal is necessary, compressed air can be used from a safe distance. ## What to Avoid Avoid contact with chemicals, acids, and cleaning agents that may react with tellurides and sulfides in the surrounding matrix. Specimens should not be subjected to ultrasonic cleaning. Temperature and humidity changes do not have a significant impact, but extreme conditions should be avoided. ## Storage Specimens should be stored under stable conditions, preferably in sealed "micromount" boxes, to protect them from dust and mechanical damage. A label with precise location and identification is crucial, as bilibinskite is impossible to identify with the naked eye.