Příbramite
Chemical formula: Cu¹⁺Sb³⁺Se²⁻₂
Příbramite is a very rare copper antimony selenide, forming microscopic, metallic-lustrous grains in association with other selenides.
Properties
- Mohs hardness
- 3-4
- Color
- Lead grey
- Luster
- Metallic
- Streak
- Black
- Density
- 5.884
- Cleavage
- None
- Fracture
- None observed
- Transparency
- Opaque
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identification of příbramite is possible only through advanced laboratory methods. It requires analysis in reflected light under a polarizing microscope and chemical analysis using an electron microprobe (EDS/WDS) to confirm its composition (presence of copper, antimony, and selenium). This is the only method that allows distinguishing it from other visually similar selenides. ## Distinguishing from similar minerals Under the microscope, příbramite can be confused with other selenides, such as umangite, berzelianite, eskebornite, or clausthalite. Differentiation is based on subtle differences in reflective color, anisotropy, and, crucially, precise chemical composition analysis. ## Crystal forms Příbramite forms only microscopic, irregular (anhedral) grains. No well-formed crystals have been observed.
Geological environment
## Genesis Příbramite forms as a result of hydrothermal processes. In its type locality (Příbram), it is associated with calcite-uraninite veins, where it crystallizes in the late stage of selenide mineralization formation. It formed in a selenium-rich environment, where selenium replaced sulfur in sulfosalt structures. ## Mineral associations This mineral occurs in close association with uraninite (in which it forms inclusions), bukovite, umangite, berzelianite, eskebornite, clausthalite, hematite, and goethite. ## Localities The only confirmed occurrence of příbramite in the world is its type locality – the historical uranium mine in the Příbram region in the Central Bohemian Region of the Czech Republic.
Rarity
Extremely rare
For collectors
## Quality criteria As a microscopic mineral, příbramite is not evaluated according to typical collector criteria such as size, color, or crystal form. The value of a specimen lies in its scientific significance and the confirmed presence of the mineral. The most valuable samples are those from the type locality, with the richest association of other rare selenides, whose presence has been analytically confirmed. ## Popular localities The only source of specimens is the type locality in Příbram, Czech Republic. These specimens are extremely difficult to obtain and primarily go to institutional collections and highly specialized collectors of microscopic minerals.
Care and storage
## Cleaning Due to its microscopic size and occurrence as inclusions in the rock matrix, individual grains of příbramite are not subject to cleaning. The host specimen should be cleaned mechanically with a very delicate, dry brush to avoid damaging potential associated minerals. ## What to avoid Avoid contact with chemicals, acids, and water, which could react with associated minerals (mainly uraninite). Specimens containing uranium minerals require caution due to their radioactivity. ## Storage Specimens with příbramite should be stored in stable conditions, in sealed containers or display cases, away from dust and moisture. They should be properly labeled, taking into account the presence of radioactive minerals.