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 1-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: 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
- C₁₃H₁₀
- Mohs hardness
- 1-2
- Density
- 1.206 g/cm³
- Colors
- Streak
- White
- Luster
- Resinous
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular crystals, massive, incrustations
- Cleavage
- None
- Fluorescence
- Bright blue under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed as a result of burning pyritic shale (Kladno, Czech Republic)
Where rockhounds find kratochvílite
Classic worldwide localities
- Kladno district, at the Nejedlý I coal mine, Libušín, Czech Republic
Field-hunting tip
Where it forms: Formed as a result of burning pyritic shale (Kladno, Czech Republic). If you start seeing coal, carbonaceous shale in float, you are in the right ground. Typical habit: tabular crystals, massive, incrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kratochvílite?+
Where is kratochvílite found?+
What rocks look like kratochvílite?+
What minerals are found with kratochvílite?+
What kind of rock does kratochvílite form in?+
What is kratochvílite used for?+
Find kratochvílite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
