Nickeline has somewhat of an identity crisis. It is alternatively known
as niccolite (mostly in Europe). Reference books often use Nickeline (Niccolite)
or Niccolite (Nickeline) as a heading. The growing trend and "official"
name is nickeline as is used here.
Its first name was the German term "Kupfer nickel" or
copper nickel. It sounds like some sort of alloy. It actually was a term
of derision because nickel meant "nixes" or underground
goblins. The miners in Germany who first saw the copper-red metallic mineral
were convinced the mineral was a rich ore of copper. Instead, try as they
might, no copper was to be produced from the nickel arsenide. The metal
that was produced from the mineral was found to be useful and valuable
and it is from this unflattering term that the metal received its
name, nickel (Ni).
Nickeline is also the name of a group of hexagonal
minerals of which the mineral nickeline is one of the more common members.
Members of the Nickeline Group have
a very simple formula, namely: AX.
Where the metal ion, A, is either cobalt,
palladium, platinum, nickel and/or iron and the X
can be either arsenic, selenium, bismuth, tellurium and/or antimony with
some members having some sulfur. All members of the group have nickeline's
basic structure. They are all hexagonal
and except for nickeline and pyrrhotite, are very uncommon to rare
These are the members of the Nickeline Group:
Langistite(Cobalt Nickel Arsenide)
Nickeline (Nickel Arsenide)
(Platinum Antimonide Bismuthinide)
(Palladium Nickel Antimonide)
Niggliite(Platinum tin), was a member of this group and shares the same
structure but is considered an alloy, having metallic bonds instead of
components. The hexagonal components are placed in the Nickeline Group,
but most natural pyrrhotite is a mixture of both components.
Nickeline's structure is fairly simple with
the nickel ions, in hexagonal packing, forming stacked identical layers
parallel to the major six-fold axis. The arsenic ions rest between the
nickel ion layers, but in a staggered or alternating sequence such that
the next layer is not in the same position as the previous layer. Each
metal ion is surrounded by six arsenics; three below and three above. The
major axis is actually a six-fold screw axis (helix) about the nickel ions.
A screw axis is an axis that has a rotation and a translation
in the major axis direction. So, in this case, the axis will start with
an arsenic ion at the base level. A rotation about the axis of 60 degrees
and then movement (approximately 2.5 angstroms) along the axis produces
the next arsenic ion. If this is done a total of six times, then the entire
structure and consequently the symmetry of nickeline is reproduced. All
members of the Nickeline Group share this basic structure, but with their
own combination of elements of course.
Nickeline is not exactly a common mineral, but is found with other nickel
and cobalt sulfide ores and thus it is included with them when mined for
their various ores. This makes nickeline a minor ore of nickel and commercially
important is some localities. The sulfides are usually hydrothermal in
origin, although nickeline is also found in basic
igneous rocks such as
gabbros. Although crystals of nickeline are very scarce, some formations
of nickeline can be attractive and an interesting addition to someone's
Color is copper-red to pink.
Luster is metallic.
Transparency: Crystals are opaque.
Crystal System: Hexagonal; 6/m 2/m 2/m
Crystal Habits are limited to mostly massive and granular components
of massive hydrothermal sulfide rocks and gabbros, but a few localities
have produced good pyramidal or tabular crystals. Columnar and reniform
habits are also seen. Rare fourling twins
are also seen.
Cleavage: Not observed.
Hardness is 5 - 5.5
Specific Gravity is approximately 7.8 (well above average for
Streak: Dark brown to black.
Other Characteristics: Will often develop a dark tarnish on
fresh surfaces and weathered surfaces may have a coating of the green nickel
Upon heating a garlic odor maybe observed due to the arsenic content. Crystals
tend to be striated.
Associated Minerals include arsenopyrite,
Notable Occurrences include the Natsume nickel mine, Japan and
at Mansfeld and Eisleben, Germany; Franklin, New Jersey; California and
Colorado, USA; Styria, Austria; Sinaloa, Mexico; Talmessi, Anarak, Iran
and at Great Slave Lake, Northwest Territories, Canada; Cobalt and Sudbury,
Ontario, Canada as well as some sites in England, France, Morocco, Russia
and southern Australia.
Best Field Indicators are color, density, associations, streak,
hardness and odor when heated.