Hyršlite

Chemical formula: Pb₂+₈As₃+₁₀Sb₃+₆S₂-₃₂

Hyršlite is a rare lead, arsenic, and antimony sulfosalt, forming acicular crystals with a metallic luster.

## Characteristics Hyršlite is a mineral from the sulfosalt group, chemically classified as a lead, arsenic, and antimony sulfide. It occurs as aggregates of fine, acicular or capillary crystals, which can form tangled masses. Individual crystals are elongated and flexible, reaching several millimeters in length. The mineral is characterized by a dark gray to black color and a strong, metallic luster. ## Physical Properties Hyršlite crystals are opaque and exhibit a metallic luster. The mineral is relatively soft, with a Mohs hardness of approximately 2.5-3. Its density is significant, around 5.61 g/cm³, which is typical for lead-bearing minerals. The crystals are flexible, which is one of its characteristic features. ## History and Name The mineral was officially recognized by the International Mineralogical Association (IMA) in 2016. Its name honors the Czech mineral collector and researcher, Stanislav Hyršl (born 1956), in recognition of his contribution to mineralogy. It was discovered in the Černý Důl mine in the Czech Republic.

Properties

Mohs hardness: 2.5-3
Luster: Metallic
Streak: Black
Density: 5.61
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Key features for identifying hyršlite are its form – aggregates of very fine, acicular or capillary crystals – and its metallic luster and dark gray color. The flexibility of individual needles is also an important diagnostic clue. ## Distinguishing from Similar Minerals It can be confused with other acicular sulfosalts, such as jamesonite, boulangerite, or zinkenite. Differentiation requires advanced analytical methods, such as X-ray spectroscopy (XRD) or chemical analysis (EDS), as these minerals are almost visually identical. ## Crystal Forms It forms acicular and capillary crystals, elongated along the [001] axis, often with striations on the faces. These crystals group into tangled, woolly, or radial aggregates.

Geological environment

## Genesis This is a hydrothermal mineral. It forms in ore veins, where it crystallizes from solutions rich in lead, arsenic, antimony, and sulfur under low to medium temperature conditions. ## Mineral Associations At the type locality (Černý Důl), it co-occurs with quartz, tennantite-(Zn), chalcopyrite, sphalerite, pyrrhotite, arsenopyrite, galena, and boulangerite. ## Localities The only confirmed and described occurrence of hyršlite in the world is its type locality: the Černý Důl mine in the Krkonoše Mountains region (Hradec Králové Region) in the Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria The most valuable specimens are those with rich, dense aggregates of well-formed, undamaged acicular crystals. Contrast with a light matrix rock (e.g., white quartz) significantly enhances the aesthetics and value of the specimen. Due to the microscopic nature of the crystals, specimens suitable for viewing without magnification are rare. ## Popular Localities The only source of specimens is the Černý Důl mine in the Czech Republic. Material from this locality is extremely rare on the collector's market.

Care and storage

## Cleaning Specimens should only be cleaned mechanically, using a very soft brush to remove dust. The use of water, especially ultrasonics, is inadvisable due to the mineral's fragility and potential reactivity. ## What to Avoid Avoid contact with chemicals, acids, and detergents. As a sulfosalt, the mineral can oxidize and tarnish due to moisture and air pollutants. Protect it from high temperatures and direct sunlight. ## Storage It is recommended to store specimens in closed, dry containers (e.g., membrane boxes or display cases) under stable room conditions. Due to the lead and arsenic content, hands should be washed after handling the mineral.

Sources

IMA Mineral List (CNMNC)