Luboržákite
Chemical formula: Mn²⁺₂As³⁺Sb³⁺S²⁻₅
A black, metallic sulfosalt from the pavonite group, a rare combination of manganese, arsenic, and antimony, discovered in Russia.
Properties
- Mohs hardness
- 4-4.5
- Luster
- Metallic
- Streak
- Black
- Density
- 4.181
- Fracture
- Irregular/Uneven
- Transparency
- Opaque
- Crystal system
- Monoclinic
Diagnostic features
## Identification Luboržákite is identified by its black color, metallic luster, and characteristic small, acicular or bladed crystals forming aggregates. A black streak is also a helpful feature. However, definitive identification requires advanced analytical methods, such as chemical composition analysis (EDS) or X-ray diffraction (XRD), due to its similarity to other sulfosalts. ## Distinguishing from similar minerals This mineral can be confused with many other black, metallic sulfosalts, such as stibnite, boulangerite, or other minerals from the pavonite group. "Eyeball" differentiation is practically impossible. The key is to examine the chemical composition – the presence of manganese, arsenic, and antimony in specific proportions is unique to luboržákite. ## Crystal forms Crystals are very small, reaching up to 0.3 mm in length. They are acicular or bladed and often combine into radial or haphazardly tangled aggregates.
Geological environment
## Genesis Luboržákite forms under low-temperature hydrothermal conditions. At its type locality (Vorontsovskoye deposit), it was found in cavities within dolomites that underwent decarbonatization and silicification processes (replacement by silica). ## Mineral associations This mineral co-occurs with other products of hydrothermal processes. At its type locality, it was found in association with quartz, dolomite, pyrite, realgar, orpiment, stibnite, getchellite, laffittite, aktashite, galkhaite, native sulfur, and rare sulfosalts such as vorontsovite and dvornikite. ## Localities The only confirmed and described occurrence of luboržákite in the world is its type locality – the Vorontsovskoye gold deposit, located in the Serov district of the Sverdlovsk Oblast, Russia.
Rarity
Extremely rare
For collectors
## Quality criteria As a "micromount" type mineral, its collector value depends on the richness and aesthetics of the crystal aggregates, rather than the size of individual crystals. The most desirable specimens are those with clearly formed, undamaged, radial clusters of acicular crystals, well-exposed on the rock matrix. Association with other rare minerals is also important. ## Popular localities The only source of collector specimens is the type locality in Russia. Any specimen originating from this location is a valuable acquisition for collectors specializing in mineral systematics or rare species.
Care and storage
## Cleaning Due to the rarity and delicate nature of the aggregates, mechanical cleaning is not recommended. If necessary, compressed air can be used to remove dust. Avoid contact with water and all chemicals. ## What to avoid Avoid contact with acids and other chemicals that may react with the mineral's components. As a sulfosalt, it may be sensitive to moisture and temperature changes. Protect it from impacts and scratching due to its brittleness and relatively low hardness. ## Storage Luboržákite specimens should be stored under stable conditions, in a dry place, away from direct sunlight and heat sources. The safest method is to store them in a sealed "micromount" box, which protects delicate crystals from mechanical damage and dust.