Kratochvílite
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.
| Kratochvílite | |
|---|---|
| General | |
| Category | Organic mineral |
| Formula (repeating unit) | C13H10 |
| Strunz classification | 10.BA.25 |
| Crystal system | Orthorhombic |
| Crystal class | Pyramidal (mmm) |
| Space group | Orthorhombic H-M symbol: (mm2) Space group: Pnam |
| Identification | |
| Color | White |
| Streak | White |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.578 nβ = 1.663 nγ = 1.919 |
| Birefringence | δ = 0.341 |
| References | [1][2][3] |
It was first described from the Nejedly mine in Bohemia, Czech Republic in 1937.[2]
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