Nickeline is a striking metallic nickel arsenide recognized by its characteristic pale copper-red color that often tarnishes to a darker greyish-brown. It is typically found in massive or reniform habits within hydrothermal vein systems associated with other nickel and cobalt minerals.
Is this nickeline?
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 nickeline with a known reference. Nickeline sits at Mohs 5-5.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale brownish black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: lead gray, grayish, copper, black.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: columnar, massive, reniform.
Often confused with
Nickeline vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Nickeline leaves pale brownish black, Breithauptite leaves reddish brown.
How to tell apart: Streak differs, so Nickeline leaves pale brownish black, Pyrrhotite leaves dark grayish black.
How to tell apart: Streak differs, so Nickeline leaves pale brownish black, Skutterudite leaves black.
Often found alongside nickeline
Minerals reported to co-occur with nickeline. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NiAs
- Mohs hardness
- 5-5.5
- Density
- 7.784 g/cm³
- Streak
- Pale brownish black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Columnar, massive, reniform
- Cleavage
- Imperfect on {1010}; imperfect on {0001}
- Rarity
- Uncommon
- Uses
- Collector, Ore of nickel
- Host rock
- A minor component of Ni–Cu ores in high-temperature hydrothermal veins; massive and in disseminations in peridotite and norite
Where rockhounds find nickeline
Classic worldwide localities
- Silver Cliff, Custer Co., and in the Gem mine, Fremont Co., Colorado, USA
- Eisleben and Mansfeld, Saxony-Anhalt, Germany
- St. Andreasberg, Harz Mountains, Germany
- Schneeberg, Saxony, Germany
- Richelsdorf, Hesse-Nassau, Germany
- Schladming, Austria
Field-hunting tip
Where it forms: A minor component of Ni–Cu ores in high-temperature hydrothermal veins; massive and in disseminations in peridotite and norite. If you start seeing skutterudite–nickel-skutterudite, safflorite, rammelsbergite in float, you are in the right ground. Typical habit: columnar, massive, reniform. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify nickeline?+
Where is nickeline found?+
Is nickeline safe to handle?+
What rocks look like nickeline?+
What minerals are found with nickeline?+
What kind of rock does nickeline form in?+
What is nickeline used for?+
Find nickeline on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
