Zálesíite is a rare arsenate mineral belonging to the Mixite group, typically found as delicate, needle-like crystals or radial sprays. It is often identified in oxidized zones of arsenic-rich deposits, distinguished primarily through chemical analysis due to its visual similarity to other members of the Mixite group.
Is this zálesíite?
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 zálesíite with a known reference. Zálesíite sits at Mohs 2-3, 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: vitreous to resinous.
- 4Match the color rangeCompare against the expected color range: pale green.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular, fibrous, powdery.
Often confused with
Zálesíite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside zálesíite
Minerals reported to co-occur with zálesíite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₆Ca(AsO₄)₂(AsO₃OH)(OH)₆·3H₂O
- Mohs hardness
- 2-3
- Density
- 3.49 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to resinous
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular, fibrous, powdery
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An oxidation product of chalcopyrite and cobalt arsenides
Where rockhounds find zálesíite
Classic worldwide localities
- Zálesí (formerly Valdek) uranium deposit, near Javorník, northern Moravia, Czech Republic (type locality)
- Hilarion mine, near Kamareza, Laurium, Attica Penninsula, Greece
- Fuka mine, Okayama Prefecture, Japan and Mazarrón-Águilas district, Murcia, Spain
Field-hunting tip
Where it forms: An oxidation product of chalcopyrite and cobalt arsenides. If you start seeing chrysocolla, malachite, clinoclase in float, you are in the right ground. Typical habit: acicular, fibrous, powdery. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify zálesíite?+
Where is zálesíite found?+
Is zálesíite safe to handle?+
What rocks look like zálesíite?+
What minerals are found with zálesíite?+
What kind of rock does zálesíite form in?+
What is zálesíite used for?+
Find zálesíite on the map
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