Niccolite
Nickel arsenide (NiAs)
A pale copper-red nickel arsenide, historically called kupfernickel, that is an ore of nickel and gives the metal its name.
- Mohs hardness
- 5-5.5
- Color
- Pale copper-red to brownish red, tarnishing grey to blackish
- Type
- mineral
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Overview
Niccolite, officially named nickeline, is a nickel arsenide (NiAs) with a distinctive pale copper-red metallic color. It is the mineral behind the word "nickel": German miners called it kupfernickel ("copper-devil's ore") because it looked like copper ore but yielded no copper, blaming a mischievous sprite.
It is opaque, metallic, and often massive or reniform rather than well-crystallized. Its surface commonly tarnishes to a duller grey or blackish film, masking the fresh copper-pink color.
As an arsenide it is associated with other arsenic-bearing nickel and cobalt minerals and is a useful ore of nickel where it occurs in quantity.
Formation & geology
Nickeline forms in hydrothermal vein deposits, especially those rich in nickel, cobalt, and silver arsenides. It crystallizes in the hexagonal system but well-formed crystals are uncommon; it usually appears massive, columnar, or in rounded reniform aggregates.
It is typically found with other arsenides such as skutterudite, safflorite, and rammelsbergite, along with native silver, native bismuth, and cobalt minerals. Important localities include the Cobalt district of Ontario, Canada; the Erzgebirge of Germany; Jachymov in the Czech Republic; and various nickel-cobalt-silver veins worldwide.
How to identify it
The key clue is the pale copper-red to brownish-pink metallic color of fresh surfaces, distinctly more pink than true copper, combined with a brownish-black streak and high specific gravity (about 7.8).
It is moderately hard (Mohs 5-5.5) and opaque. Heating or acid testing releases a garlic-like arsenic odor, confirming an arsenide. Look-alikes include native copper (which is more truly red, softer, and very malleable) and pyrrhotite or breithauptite (the antimony analogue, which is more violet-pink). A tarnished grey film is common, so examine a fresh break.
Uses & significance
Niccolite is an ore of nickel and has been mined where it occurs abundantly, though arsenides are less desirable than sulfide nickel ores because of the arsenic content. Historically it was important in the early understanding and naming of nickel.
Today it is mainly of interest to mineral collectors and for its place in mining history. It has no significant gemstone or metaphysical use. Care should be taken when handling because it contains arsenic; dust should not be inhaled or ingested.
Frequently asked questions
Why is niccolite also called nickeline?
Nickeline is the official IUPAC/IMA-accepted name; niccolite is the older traditional name still widely used by collectors.
Where does the name nickel come from?
From the German kupfernickel, meaning copper-devil, given by miners who found the ore looked coppery but produced no copper.
Is niccolite dangerous to handle?
It contains arsenic, so avoid inhaling dust or handling broken material with bare hands for long periods; wash hands after handling.
How can I tell niccolite from copper?
Niccolite is paler and pinker, harder, much denser, brittle rather than malleable, and gives an arsenic garlic smell when heated.
Niccolite guides
In-depth guides for identifying, valuing, and understanding Niccolite.
Niccolite identified by the community
Real specimens identified with Rock Identifier.
