Kratochvílite

Chemical formula: C₁₃H₁₀

Kratochvilite is a very rare, organic mineral, a natural aromatic hydrocarbon, occurring as brittle, colorless or yellowish coatings and crystals.

## Characteristics Kratochvilite is a naturally occurring aromatic hydrocarbon, closely related to fluorene. It forms very small, tabular or lath-like crystals, which rarely exceed a few millimeters in length. Most often, it occurs as thin coatings, crusts, or small crystalline aggregates on host rocks, such as shales or coal. It is a very brittle and soft mineral. ## Physical Properties Kratochvilite crystals are characterized by a hardness of only 1-2 on the Mohs scale, which makes them extremely delicate. They have a vitreous to resinous luster. They are transparent to translucent. Due to their nature, specimens are very light. ## Colors and Varieties This mineral is usually colorless, white, yellowish, or pale yellow. No color or commercial varieties are distinguished. ## History and Name Kratochvilite was first described in 1937 by Czech mineralogists Jaroslav Kokta and Radim Nováček. The mineral is named in honor of Josef Kratochvíl (1878-1958), a Czech professor of petrography and economic geology at Charles University in Prague, author of a multi-volume work on the mineralogical topography of Bohemia. ## Uses Kratochvilite has no industrial application. Its significance is purely scientific and as a collector's item, as an example of a rare organic mineral.

Properties

Mohs hardness: 1-2
Color: Colorless
Luster: Vitreous, Resinous
Streak: White
Density: 1.206
Cleavage: Perfect on {001}
Fracture: Micaceous
Transparency: Translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Kratochvilite is identified by its extreme softness and brittleness, low melting point, and characteristic occurrence as small, tabular crystals on carbonaceous shales or in coal mines. Under ultraviolet radiation, it exhibits intense blue fluorescence. ## Distinguishing from Similar Minerals It can be confused with other rare organic minerals, such as evenkite or idrialite, which occur in similar environments. Differentiation requires advanced analytical methods, but strong blue fluorescence is a fairly characteristic feature of kratochvilite. ## Crystal Forms It forms thin, tabular or lath-like crystals with a rhombic cross-section, often flattened. It also occurs as fine-grained aggregates, coatings, and thin crusts.

Geological environment

## Genesis Kratochvilite is a mineral of organic origin. It forms as a result of low-temperature hydrothermal processes or during underground fires in hard coal and bituminous shale deposits. It crystallizes from hydrocarbon-rich gases and vapors, depositing in fissures and on rock surfaces. ## Mineral Associations It often co-occurs with native sulfur, realgar, orpiment, and other organic minerals such as idrialite. It is usually accompanied by carbonaceous or bituminous material. ## Localities The most important localities worldwide are the type locality in Kladno (Czech Republic), as well as coal mines in the vicinity of Ostrava (Czech Republic) and Göttelborn (Saarland, Germany). It also occurs in coal mines in Pennsylvania (USA).

Rarity

Very rare

For collectors

## Quality Criteria The most prized specimens are those with well-formed crystals visible to the naked eye, which is a great rarity. An aesthetic composition with contrasting host rock is also important. Due to the nature of the mineral, even microscopic but well-formed crystals are considered valuable. ## Popular Localities Classic and most sought-after specimens come from historical localities in the Czech Republic (Kladno, Ostrava region) and from coal mines in the Saarland region of Germany.

Care and storage

## Cleaning Kratochvilite specimens are extremely delicate and sensitive. Mechanical cleaning is not recommended. If necessary, compressed air can be used very carefully (from a safe distance) to remove loose dust. Avoid contact with water and all chemicals. ## What to Avoid The mineral is sensitive to heat and can melt at temperatures around 83-86°C. It should be protected from direct sunlight, which can cause its degradation. It is soluble in alcohol, ether, and other organic solvents. Contact with water can damage the delicate crystals. ## Storage Specimens should be stored in sealed, stable containers (e.g., "micromount" type), away from sources of heat, light, and moisture. Due to its brittleness, avoid vibrations and any physical contact.