Ježekite is a rare sodium uranium sulfate, typically sulfuric-yellow. It was approved as a distinct mineral species in 2014. It was first described from Geschieber vein, Svornost mine, Jáchymov, Western Bohemia, Czech Republic.
Is this ježekite?
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 ježekite with a known reference. Ježekite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ježekite leaves a pale yellow streak.
- 3Read the lusterHold the specimen under a strong light. Ježekite typically shows a vitreous to pearly luster.
- 4Match the color rangeCompare against the expected color range: sulfuric-yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: tabular crystals.
Often confused with
Ježekite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ježekite leaves pale yellow, Cerussite leaves white; luster reads vitreous to pearly on Ježekite and adamantine on Cerussite.
How to tell apart: Streak differs, so Ježekite leaves pale yellow, Phosgenite leaves white; luster reads vitreous to pearly on Ježekite and adamantine on Phosgenite.
Often found alongside ježekite
Minerals reported to co-occur with ježekite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₈[(UO₂)(CO₃)₃](SO₄)₂·3H₂O
- Mohs hardness
- 3.5
- Density
- 2.966 g/cm³
- Colors
- Streak
- Pale Yellow
- Luster
- Vitreous to Pearly
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect On {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
Where rockhounds find ježekite
Classic worldwide localities
- Jachymov, Czech Republic
Field-hunting tip
Look in hydrothermal veins country, the host setting where ježekite typically forms. If you start seeing uranyl carbonates, quartz in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ježekite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
