Kratochvílite is a rare organic mineral belonging to the hydrocarbon group, typically forming within burning coal seams. It is most easily identified by its distinct blue fluorescence under ultraviolet light and its low density, often appearing as pale, waxy tabular crystals or crusts.
Is this kratochvílite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch kratochvílite with a known reference. Kratochvílite sits at Mohs 1 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kratochvílite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Kratochvílite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: yellow, colorless, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, massive, incrustations.
Often confused with
Kratochvílite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside kratochvílite
Minerals reported to co-occur with kratochvílite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- C₁₄H₁₀
- Mohs hardness
- 1
- Density
- 1.10 g/cm³
- Streak
- White
- Luster
- Resinous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals, Massive, Incrustations
- Cleavage
- None
- Fluorescence
- Bright Blue Under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Coal Seams
- Typical price
- $20-150 thumbnail
Where rockhounds find kratochvílite
Classic worldwide localities
- Czech Republic
- Germany
Field-hunting tip
Look in coal seams country — that is the host setting where kratochvílite typically forms. If you start seeing coal, carbonaceous shale in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, incrustations habit, so train your eye for that shape before scanning the outcrop.


