Lemanskiite is a very rare secondary arsenate mineral found in the oxidation zones of arsenic-rich copper deposits. Collectors typically search for its small, distinct, pseudo-tetragonal crystals often associated with other copper minerals.
Is this lemanskiite?
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 lemanskiite with a known reference. Lemanskiite sits at Mohs ~2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark blue.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: aggregates, rosette.
Often confused with
Lemanskiite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Euchroite is the harder of the two (Mohs 3.5-4 vs. ~2.5); streak differs, so Lemanskiite leaves light blue, Euchroite leaves green.
How to tell apart: Streak differs, so Lemanskiite leaves light blue, Olivenite leaves olive-green to brown; luster reads vitreous on Lemanskiite and adamantine to vitreous, pearly to silky if fibrous on Olivenite.
Often found alongside lemanskiite
Minerals reported to co-occur with lemanskiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCaCu₅(AsO₄)₄Cl(H₂O)₃
- Mohs hardness
- ~2.5
- Density
- 3.78 g/cm³
- Colors
- Streak
- Light blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Aggregates, rosette
- Cleavage
- Excellent on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral, as nodules or veinlets in gold-bearing quartz veins of a hydrothermal deposit
Where rockhounds find lemanskiite
Classic worldwide localities
- Abundancia gold mine, El Guanaco mining district, south of Cerro La Estrella, ~ 95 km east of Taltal, Region II, Antofagasta Province, Chile
Field-hunting tip
Where it forms: A secondary mineral, as nodules or veinlets in gold-bearing quartz veins of a hydrothermal deposit. If you start seeing lammerite, olivenite, mansfieldite in float, you are in the right ground. Typical habit: aggregates, rosette. Train your eye for that shape before scanning the outcrop.
Common questions
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Find lemanskiite on the map
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