Antimonselite
Chemical formula: Sb<sup>3+</sup><sub>2</sub>Se<sup>2-</sup><sub>3</sub>
Antimonselite is a rare antimony selenide, forming acicular crystals and aggregates with a metallic luster, found in hydrothermal ore veins.
Properties
- Mohs hardness
- 2.5-3
- Luster
- Metallic
- Streak
- Black
- Density
- 5.95
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Antimonselite can be identified by its characteristic form – long, acicular or capillary crystals forming tangled aggregates. Key features also include a lead-gray color, metallic luster, low hardness, and perfect cleavage along the crystal axes. It reacts with nitric acid. ## Distinguishing from Similar Minerals Antimonselite is visually almost identical to stibnite (Sb₂S₃). Distinguishing these two minerals without advanced chemical analysis (e.g., EDS) is practically impossible. Other rare sulfosalts and selenides, such as guanajuatite or bismuthinite, also have a similar appearance, and distinguishing them also requires specialized studies. ## Crystal Forms Crystals are always strongly elongated, acicular (needle-like habit), often arranged in chaotic, tangled masses (felt-like aggregates) or forming radial clusters. Less commonly, it occurs as granular aggregates.
Geological environment
## Genesis Antimonselite is a mineral of hydrothermal origin. It forms in ore veins developing under low and medium temperature conditions. Its crystallization requires a specific geochemical environment, rich in both antimony and selenium. ## Mineral Associations It most often co-occurs with other selenides and sulfides. Typical associated minerals include: native selenium, clausthalite, tiemannite, klockmannite, umangite, pyrite, chalcopyrite, and quartz and calcite as vein minerals. ## Localities The most important and classic localities for antimonselite are: - Bolivia: El Dragón mine in Antonio Quijarro Province, where some of the world's best specimens have been found. - Argentina: Sierra de Cacho, La Rioja Province. - USA: Comstock Lode mine in Nevada (type locality). - China: Yutangba selenium deposit in Hubei Province. - Czech Republic: Předbořice in the Central Bohemian Region.
Rarity
Very rare
For collectors
## Quality Criteria Most valued by collectors are specimens with well-formed, lustrous acicular crystals, forming aesthetic, radial or tangled groups on a contrasting rock matrix. The size and richness of antimonselite aggregates significantly increase the value of the specimen. Analytically confirmed locality is also important, especially from classic sites like the El Dragón mine. ## Popular Localities Specimens from the Bolivian El Dragón mine are considered the best in the world and serve as a benchmark for this mineral. Material from Argentina and China is also sought after.
Care and storage
## Cleaning Antimonselite specimens are very delicate and brittle. Cleaning should be kept to an absolute minimum. If necessary, compressed air can be used to remove dust. Avoid contact with water and any chemicals. ## What to Avoid Avoid ultrasonic cleaners, which can destroy the fragile crystals. The mineral is sensitive to shocks and impacts. Prolonged exposure to humid air can lead to slow oxidation. ## Storage It is recommended to store specimens in closed, padded collector boxes to protect them from mechanical damage, dust, and humidity. It should be kept away from other minerals that could scratch or damage it.