Hodrušite
Chemical formula: Cu<sup>1+</sup><sub>4</sub>Bi<sup>3+</sup><sub>6</sub>S<sup>2-</sup><sub>11</sub>
Hodrushite is a rare copper-bismuth sulfide, forming acicular crystals with a metallic luster, found in hydrothermal veins.
Properties
- Mohs hardness
- 4
- Luster
- Metallic
- Streak
- Black
- Density
- 6.45
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Monoclinic
Diagnostic features
## Identification Hodrushite can be identified by its characteristic form – long, acicular or bladed crystals, often forming radial aggregates. Key features also include a metallic luster, tin-white or steel-gray color, and high density. It occurs in paragenesis with other sulfides and sulfosalts of bismuth and copper. ## Distinguishing from Similar Minerals Hodrushite can be confused with other acicular sulfosalts, such as bismuthinite (Bi₂S₃) or aikinite (PbCuBiS₃). Bismuthinite is usually more lead-gray and has a slightly lower hardness. Aikinite often forms thicker, prismatic crystals. Definitive distinction requires advanced analytical methods, such as chemical analysis (EDS) or X-ray diffraction (XRD). ## Crystal Forms Hodrushite crystals are elongated along one axis, forming acicular, bladed, or hair-like shapes. They usually occur as radial, stellate, or haphazardly tangled aggregates. Less commonly, they are found as single crystals embedded in quartz.
Geological environment
## Genesis Hodrushite is a mineral of hydrothermal origin. It forms in medium to high-temperature (meso- and hypothermal) ore veins that cut through volcanic rocks, such as andesites and dacites. It crystallizes from solutions rich in copper, bismuth, and sulfur. ## Mineral Associations This mineral often co-occurs with other sulfides and sulfosalts. Its most common associated minerals include chalcopyrite, bismuthinite, quartz, hematite, pyrite, as well as other rarer bismuth minerals, such as emplectite, wittichenite, or paderaita (of which hodrushite is a dimorph). ## Localities The most important and classic occurrence of hodrushite is its type locality – the Rozália deposit in Hodruša-Hámre, Slovakia. It is also known from several other locations worldwide, including the Botevo mine in Bulgaria, the Ulsan deposit in South Korea, the Salave mine in Spain, and several sites in Japan (Oya and Kushikino mines).
Rarity
Rare
For collectors
## Quality Criteria The most valued specimens by collectors are those with well-formed, sharp, and undamaged crystals, forming aesthetic, radial aggregates. The contrast with clear quartz, on which the crystals are embedded, significantly enhances visual appeal. The size of the aggregates and the luster of the crystals also have a significant impact on the specimen's value. Confirmed analysis, distinguishing it from similar sulfosalts, is also important. ## Popular Localities By far the most sought-after and classic specimens come from the type locality – the Rozália mine in Hodruša-Hámre, Slovakia. Specimens from this location are considered exemplary for the species and fetch the highest prices in the collector's market.
Care and storage
## Cleaning Hodrushite specimens are very delicate and brittle. Cleaning should be limited to an absolute minimum. If necessary, a soft brush can be used to remove dust. Water and any chemicals that could cause oxidation or damage to the delicate crystals should be avoided. ## What to Avoid Contact with water, acids, detergents, and other chemicals must be strictly avoided. The crystals are very brittle, so the specimen should be protected from impacts, vibrations, and abrasion. Prolonged exposure to humid air can lead to oxidation and surface tarnishing. ## Storage It is recommended to store hodrushite specimens in closed, dry containers (e.g., "micromount" boxes) away from dust and moisture. To prevent oxidation, desiccants can be used. Due to its brittleness, the specimen should not be placed in direct contact with other, harder minerals.