Nickeltalmessite is a rare nickel-dominant arsenate belonging to the fairfieldite group, typically found as attractive green crystalline coatings or small sprays. Collectors prize it for its bright color and association with other rare secondary arsenate minerals in oxidized ore zones.
Is this nickeltalmessite?
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 nickeltalmessite with a known reference. Nickeltalmessite 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. Nickeltalmessite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Nickeltalmessite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, yellowish-green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: bladed, drusy crusts, spherulitic aggregates.
Often confused with
Nickeltalmessite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside nickeltalmessite
Minerals reported to co-occur with nickeltalmessite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Ni(AsO₄)₂·2H₂O
- Mohs hardness
- 3.5
- Density
- 3.60 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Bladed, Drusy Crusts, Spherulitic Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins Containing Arsenic and Nickel Mineralization
- Typical price
- $20-200 per specimen depending on quality and matrix
Where rockhounds find nickeltalmessite
Classic worldwide localities
- Schneeberg, Saxony, Germany
- Bou Azzer, Morocco
- Lavrion District, Greece
Field-hunting tip
Look in hydrothermal veins containing arsenic and nickel mineralization country — that is the host setting where nickeltalmessite typically forms. If you start seeing arsenolite, picropharmacolite, annabergite in float, you are in the right ground. Field specimens usually show a bladed, drusy crusts, spherulitic aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify nickeltalmessite?+
Where is nickeltalmessite found?+
How much is nickeltalmessite worth?+
Is nickeltalmessite safe to handle?+
What rocks look like nickeltalmessite?+
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Find nickeltalmessite on the map
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