Kratochvilite is a rare organic mineral formed by combustion of coal or pyritic black shale deposits. It is a rare organic mineral, an orthorhombic hydrocarbon formed by combustion of coal or pyritic black shale deposits. It is a hydrocarbon with the formula of either C13H10 or (C6H4)2CH2.
It was first described from the Nejedly mine in Bohemia, the Czech Republic in 1937.
- Category: Organic mineral
- Formula: C13H10 or (C6H4)2CH2.
- Crystal system: Orthorhombic
- Crystal class: Pyramidal (mmm)
- Space group: Orthorhombic.
It is a polymorph of the aromatic hydrocarbon fluorene. It forms white, yellow to brown crystals in the orthorhombic system which occurs often as a druzy encrustation. It has a specific gravity of 1.21 and a Mohs hardness of 1 to 2.
- Colour: White
- Streak: White
- Optical properties: Biaxial (+)
- Density: 1.21
- Hardness: 1-2 – Between Talc and Gypsum
- Transparency: Translucent.
Occurrence: Formed as a result of burning pyritic shale (Kladno, Czech Republic).