| Kratochvílite | |
| Category: | Organic mineral |
| Formula: | C13H10 |
| Imasymbol: | Ktc[1] |
| Strunz: | 10.BA.25 |
| Class: | Pyramidal (mmm) |
| Symmetry: | Orthorhombic H-M symbol: (mm2) Space group: Pnam |
| Color: | White |
| Streak: | White |
| Opticalprop: | Biaxial (+) |
| Refractive: | nα = 1.578 nβ = 1.663 nγ = 1.919 |
| Birefringence: | δ = 0.341 |
| References: | [2] [3] [4] |
Kratochvilite is a rare organic mineral formed by combustion of coal or pyritic black shale deposits. It is a hydrocarbon with the formula of either C13H10 or (C6H4)2CH2. It is a polymorph of the aromatic hydrocarbon fluorene. It forms white, yellow to brown crystals in the orthorhombic system which occur often as a druzey encrustation. It has a specific gravity of 1.21 and a Mohs hardness of 1 to 2.
It was first described from the Nejedly mine in Bohemia, Czech Republic in 1937.[3]