Jolliffeite is a rare selenide mineral with formula NiAsSe or . It is the

selenium Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ...

analogue of the

sulfide mineral The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the ...

gersdorffite Gersdorffite is a nickel arsenic sulfide mineral with formula NiAsS. It crystallizes in the isometric system showing diploidal symmetry. It occurs as euhedral to massive opaque, metallic grey-black to silver white forms. Gersdorffite belongs to ...

, NiAsS, with a common impurity of

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, pr ...

, CoAsSe. It is named for its discoverer, Alfred Jolliffe, (1907–1988), a Canadian geologist of

Queen's University Queen's or Queens University may refer to: *Queen's University at Kingston, Ontario, Canada *Queen's University Belfast, Northern Ireland, UK **Queen's University of Belfast (UK Parliament constituency) (1918–1950) **Queen's University of Belfast ...

Kingston, Ontario Kingston is a city in Ontario, Canada. It is located on the north-eastern end of Lake Ontario, at the beginning of the St. Lawrence River and at the mouth of the Cataraqui River (south end of the Rideau Canal). The city is midway between Toro ...

Crystallography

Jolliffeite has cubic symmetry and is therefore isometric meaning crystallographically, it contains three perpendicular axes of equal lengths. It has four three-fold axes all inclined at the same angle to the crystallographic axes. Optically, Jolliffeite is

isotropic Isotropy is uniformity in all orientations; it is derived . Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix ' or ', hence ''anisotropy''. ''Anisotropy'' is also used to describe ...

. Isotropic minerals have a single refractive index and are not birefringent. The single

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

of Jolliffeite can be determined by its

relief Relief is a sculptural method in which the sculpted pieces are bonded to a solid background of the same material. The term ''relief'' is from the Latin verb ''relevo'', to raise. To create a sculpture in relief is to give the impression that the ...

Discovery and Importance

Jollifeite was discovered in 1991 within a

fracture zone A fracture zone is a linear feature on the ocean floor—often hundreds, even thousands of kilometers long—resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics. Lithospheric plates on eit ...

near a contact of an intrusive

peridotite Peridotite ( ) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high prop ...

with

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

from the Fish Hook Bay area, Shirley Peninsula, north shore of Lake Athabaska,

Saskatchewan Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, in a geological environment with high concentration of platinum group elements. The area of the Shirley Peninsula consists of rocks mainly Archean in age. The rare finding of Jolliffeite in this region is helping geologists piece together more of the area's history. Its composition of nickel and arsenic makes it important for mineral resources as the two have many common uses. Jollifeite's presence may also lead to the finding of other important minerals as it was found in the drill core with chalcopyrite, pyrite,

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

, arsenopyrite, bornite,

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

, quartz,

cofinite In mathematics, a cofinite subset of a set X is a subset A whose complement in X is a finite set. In other words, A contains all but finitely many elements of X. If the complement is not finite, but it is countable, then one says the set is cocoun ...

, pitchblende,

native gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile met ...

, native silver, cobaltite, and

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

References

*Jambor, J., and Vanko, D. (1992) New Mineral Names. American Mineralogist, 77, 447. *Martin, R.F. (1991) Jolliffeite and CoAsSe From Lake Athabasca. Canadian Mineralogist, 29, 411–418. {{Refend Nickel minerals Arsenic minerals Selenide minerals Cubic minerals Minerals in space group 205