Selenodantopaite
Chemical formula: Ag¹⁺₅Bi³⁺₁₃Se²⁻₂₂
Selenodantopaite is a rare silver-bismuth selenide, forming microscopic, metallic inclusions in other minerals.
Properties
- Mohs hardness
- 3.5-0
- Color
- dark grey
- Luster
- Metallic
- Density
- 7.403
- Cleavage
- Undetectable
- Fracture
- Irregular/Uneven
- Transparency
- Opaque
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of selenodantopaite is impossible without advanced laboratory equipment. It requires analysis by reflected light microscopy and chemical analysis using an electron microprobe (EDS/WDS) to confirm its composition (dominance of Ag, Bi, and Se). It is a mineral identifiable only at the microscopic level. ## Distinguishing from Similar Minerals Under the microscope, selenodantopaite is very similar to other bismuth selenides and sulfosalts, such as dantopaite, clausthalite, bohdanowiczite, or umangite. Distinguishing it from dantopaite requires chemical analysis showing the dominance of selenium over sulfur. It differs from clausthalite by a slightly brighter hue and the lack of characteristic, perfect cleavage. ## Crystal Forms This mineral forms exclusively anhedral (irregular), rounded grains and aggregates of microscopic size, usually not exceeding 150 µm. It has not been observed in the form of well-developed crystals.
Geological environment
## Genesis Selenodantopaite forms under hydrothermal conditions, in calcite-hematite veins with selenide mineralization. At the type locality (Předbořice, Czech Republic), it is associated with low-temperature processes that led to the concentration of selenium, bismuth, and silver. ## Mineral Associations This mineral occurs in close association with clausthalite (often as inclusions within it), hematite, calcite, petroviceite, umangite, eskebornite, chameanite, uraninite, and also with its sulfur analog - dantopaite. ## Localities The only confirmed and described occurrence of selenodantopaite in the world is its type locality: the former Předbořice uranium mine, located near the town of Krásná Hora nad Vltavou in the Central Bohemian Region, Czech Republic.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a selenodantopaite specimen is assessed solely through its scientific and locality value. Since the mineral is invisible to the naked eye, its value is determined by the richness of the mineral association on the specimen and the confirmation of selenodantopaite's presence through laboratory analysis. The specimen itself does not possess aesthetic qualities related to this specific mineral. ## Popular Localities The only source of specimens is the historic Předbořice mine in the Czech Republic. Material from this locality is extremely rare and available almost exclusively in specialized systematic collections and scientific institutions.
Care and storage
## Cleaning Specimens containing microscopic grains of selenodantopaite should be cleaned with the utmost care. The safest method is to use compressed air to remove dust. Any contact with water or chemicals is inadvisable due to the potential reactivity of associated minerals. ## What to Avoid Avoid all chemical agents, especially acids, which can damage both selenodantopaite and the surrounding minerals. Also, avoid ultrasonics and mechanical cleaning (e.g., with brushes), which could damage the delicate surface of the specimen and the microscopic inclusions. ## Storage Specimens containing selenodantopaite should be stored under stable conditions, in a dry place, away from direct sunlight and contaminants. It is best to keep them in sealed collector's boxes (so-called "membrane boxes"), which protect against dust and mechanical damage.