Nickellotharmeyerite is a rare arsenic-bearing mineral belonging to the Tsumcorite group. It is typically found as small, vibrant yellow to orange prismatic crystals or crusts in the oxidation zones of ore deposits. Due to its rarity and specific chemical requirements, it is primarily a target for advanced mineral collectors.
Is this nickellotharmeyerite?
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 nickellotharmeyerite with a known reference. Nickellotharmeyerite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light brown to yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: subadamantine.
- 4Match the color rangeCompare against the expected color range: yellow, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: aggregates, encrustations, microscopic crystals.
Often confused with
Nickellotharmeyerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Nickellotharmeyerite leaves light brown to yellow, Tsumcorite leaves yellow; luster reads subadamantine on Nickellotharmeyerite and vitreous on Tsumcorite.
How to tell apart: Luster reads subadamantine on Nickellotharmeyerite and adamantine on Cobalttsumcorite.
Often found alongside nickellotharmeyerite
Minerals reported to co-occur with nickellotharmeyerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaNi₂(AsO₄)₂·2H₂O
- Mohs hardness
- 4.5
- Density
- 4.45 g/cm³
- Streak
- Light brown to yellow
- Luster
- Subadamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Aggregates, encrustations, microscopic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidation zone of polymetallic ore deposits
Where rockhounds find nickellotharmeyerite
Classic worldwide localities
- Pucher shaft, near Scheeberg, Saxony, Germany (type locality)
- Dumps of the old Km-3 mine, Lavrion mining district, Attikí Prefecture, Greece
- Bou Azzer As-Co-Ni-Ag-Au deposit, Anti-Atlas, Morocco
Field-hunting tip
Where it forms: In the oxidation zone of polymetallic ore deposits. If you start seeing quartz, mawbyite, cobaltlotharmeyerite in float, you are in the right ground. Typical habit: aggregates, encrustations, microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find nickellotharmeyerite on the map
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