Litochlebite

Chemical formula: Ag₁+₂Pb₂+Bi₃+₄Se₂-₈

Litochlebit is a rare silver, lead, and bismuth selenide, forming metallic-lustered grains and aggregates embedded in calcite.

## Characteristics Litochlebit is a mineral from the sulfosalt group, specifically a selenosalt, with a complex chemical composition containing silver, lead, and bismuth. It occurs as anhedral (lacking well-formed crystal faces) grains or aggregates up to several millimeters in size, embedded in calcite veins. Its appearance is typical for many sulfosalts – it has a steel-gray color and a strong, metallic luster. It does not form well-developed, independent crystals, making its visual identification without specialized equipment impossible. ## Physical Properties This mineral is characterized by a metallic luster and is opaque. Its Mohs hardness is approximately 3.5, classifying it as a relatively soft mineral. The density is high, due to the presence of heavy elements like lead and bismuth, and is about 7.81 g/cm³. ## Colors and Varieties Litochlebit has a uniform, steel-gray color. Under a polarizing microscope in reflected light, it appears creamy white. No colored or commercial varieties are known. ## History and Name The mineral's name honors the Czech mineralogist and geologist, Jiří Litochleb (1948-2014), in recognition of his contribution to the study of ore mineralization, including uranium deposits in the Czech Republic. Litochlebit was approved as a new mineral species by the International Mineralogical Association (IMA) in 2008. It was discovered in the historic Zálesí deposit in the Czech Republic. ## Applications Due to its extreme rarity and occurrence as small grains, litochlebit has no industrial applications. It is solely an object of scientific and collecting interest for specialized collectors of rare minerals (so-called "micromounts").

Properties

Mohs hardness: 3.5
Luster: Metallic
Streak: Black
Density: 7.81
Cleavage: Indiscernible
Fracture: Uneven
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Amateur identification of litochlebit is practically impossible. It requires advanced laboratory methods, such as chemical composition analysis (EDS/WDS) using an electron microprobe and X-ray diffraction (XRD) analysis. In a hand sample, it can be suspected based on its steel-gray color, metallic luster, high density, and co-occurrence with other selenides in calcite veins at known localities. ## Distinguishing from Similar Minerals Litochlebit is macroscopically indistinguishable from many other sulfosalts and selenosalts, such as clausthalite, naumannite, bohdanowiczite, or umangite, with which it often co-occurs. Definitive differentiation is only possible based on chemical and structural analysis. ## Crystal Forms This mineral occurs as anhedral (allotriomorphic) grains and their aggregates, not exceeding a few millimeters in size. No euhedral, well-formed crystals have been observed.

Geological environment

## Genesis Litochlebit is a hydrothermal mineral. It forms in calcite-hematite veins cutting metamorphic rocks. Its crystallization occurs at relatively low temperatures from solutions rich in selenium, bismuth, lead, and silver. ## Mineral Associations This mineral occurs in association with other, often rare, selenides. At the type locality (Zálesí), its co-occurrence has been noted with clausthalite, bohdanowiczite, umangite, berzelianite, eskebornite, bukovite, as well as with hematite, calcite, and quartz. ## Localities The only confirmed and described occurrence of litochlebit in the world is its type locality – the historic uranium deposit of Zálesí near Javorník in the Rychlebské Mountains (Góry Złote) in the Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a litochlebit specimen is primarily assessed based on the size and richness of its grain aggregates against the matrix (usually white calcite). The most prized samples are those where the grains are clearly visible, numerous, and form rich aggregates. The presence of other rare selenides on the same specimen significantly increases its scientific and collector value. ## Popular Localities The only source of collector specimens is the historic mine in Zálesí, Czech Republic. The material primarily comes from old dumps and is acquired by specialized collectors.

Care and storage

## Cleaning Litochlebit specimens, usually in the form of embedded grains in calcite, should be cleaned very carefully. The safest method is to use a soft brush to remove dust. Avoid washing with water, and especially avoid using ultrasonic cleaners, which can damage delicate grains and the surrounding calcite. ## What to Avoid Contact with acids and other chemicals that can react with both litochlebit and its associated calcite should be strictly avoided. The mineral is soft and susceptible to scratching. Prolonged exposure to humid air can lead to slow oxidation and tarnishing of its metallic surface. ## Storage It is recommended to store specimens in stable conditions, in closed, dry containers (e.g., "micromount" boxes), to protect them from dust, moisture, and mechanical damage. Exposure should be away from direct sunlight and heat sources.

Sources

IMA Mineral List (CNMNC)