Zdenĕkite is an extremely rare secondary mineral that typically occurs as small, translucent yellow hexagonal plates within oxidized hydrothermal ore deposits. It is best identified through its distinct micaceous habit and limited type localities, primarily associated with the Jáchymov mining district. Due to its rarity, it is almost exclusively sought by systematic mineral collectors.
Is this zdenĕkite?
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 zdenĕkite with a known reference. Zdenĕkite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Zdenĕkite leaves a yellowish-white streak.
- 3Read the lusterHold the specimen under a strong light. Zdenĕkite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: hexagonal plates, micaceous aggregates.
Often confused with
Zdenĕkite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Zdenĕkite leaves yellowish-white, Woodwardite leaves white; luster reads vitreous on Zdenĕkite and pearly on Woodwardite.
How to tell apart: Connellite is the harder of the two (Mohs 3 vs. 2); streak differs — Zdenĕkite leaves yellowish-white, Connellite leaves pale blue.
Often found alongside zdenĕkite
Minerals reported to co-occur with zdenĕkite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaZn₄(SO₄)(OH)₆Cl·6H₂O
- Mohs hardness
- 2
- Density
- 3.37 g/cm³
- Colors
- Streak
- Yellowish-white
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Hexagonal Plates, Micaceous Aggregates
- Cleavage
- Perfect On {0001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find zdenĕkite
Classic worldwide localities
- Jáchymov, Czech Republic
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where zdenĕkite typically forms. If you start seeing gordaite, gymnite, gypsum in float, you are in the right ground. Field specimens usually show a hexagonal plates, micaceous aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find zdenĕkite on the map
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