Kratochvílite

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Kratochvílite
General
CategoryOrganic mineral
Formula
(repeating unit)
C13H10
Strunz classification10.BA.25
Crystal systemOrthorhombic
Crystal classPyramidal (mmm)
Space groupOrthorhombic
H-M symbol: (mm2)
Space group: Pnam
Identification
ColorWhite
StreakWhite
Optical propertiesBiaxial (+)
Refractive indexnα = 1.578 nβ = 1.663 nγ = 1.919
Birefringenceδ = 0.341
References[1][2][3]

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.[2]

References[edit]