Skaergaardite
Encyclopedia
Skaergaardite is an intermetallic platinum group
mineral with the general chemical formula Pd
Cu
. The mineral is named after its discovery location: the Skaergaard intrusion
, Kangerdlugssuaq area, East Greenland
. The mineral name was approved by the International Mineralogical Association
in 2003. The mineral has also been reported in the Duluth intrusion
in Minnesota
and the Rum layered intrusion in Scotland
.
. It is found as inclusions
in titanian
magnetite
, ilmenite
, pyroxenes, and plagioclase
. Skaergaardite can occur as an inclusion by itself, but is more commonly found in composite microglobule inclusions of copper iron sulfide mineral
s and other precious metal bearing minerals.
and a hexoctahedral crystal class (Hermann–Mauguin notation: 4/m2/m). Skaergaardite can appear in various forms including: droplets; cubic grains with rounded outlines; euhedral to subhedral grains; and irregular grains or aggregates.
or chalcopyrite
) or bright white (in the presence of digenite
or chalcocite
). When the mineral is rotated on the microscope stage its color does not change, indicating that it is non-pleochroic.
Under crossed polar light, skaergaardite appears completely dark no matter the direction the stage is rotated, indicating that the mineral is isotropic. As skaergaardite is isotropic, it is also non-birefringent.
(Pd), one of the six platinum group
metals (PGM) that are some of the rarest elements on earth. With the cost of palladium expected to increase as demand becomes greater, Skaergaardite could begin to be mined for its valuable palladium resources.
The Skaergaard intrusion is the only known source of skaergaardite large enough to be mined. Skaergaardite is the most common PGM mineral in the intrusion, making up over 90% of all the PGM observed. The most mineral rich layer of the intrusion could contain over 1000 tons of skaergaardite. In addition to palladium: gold
, platinum
, and other precious metals have been found in the intrusion. Interest has been increasing for an underground mine in the Skaergaard intrusion. A pre-feasibility study is currently under way and is scheduled for completion by December 2011.
Platinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...
mineral with the general chemical formula Pd
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
Cu
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
. The mineral is named after its discovery location: the Skaergaard intrusion
Skaergaard intrusion
The Skaergaard intrusion is a layered igneous intrusion in East Greenland. It comprises various rock types including gabbro, ferro diorite, anorthosite and granophyre.Discovered by Lawrence Wager...
, Kangerdlugssuaq area, East Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
. The mineral name was approved by the International Mineralogical Association
International Mineralogical Association
The International Mineralogical Association is an international group of 38 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 4000 plus known mineral species...
in 2003. The mineral has also been reported in the Duluth intrusion
Duluth Complex
The Duluth Complex, the related Beaver Bay Complex , and the associated North Shore Volcanic Group are rock formations which comprise much of the basement bedrock of the northeastern part of the U.S. state of Minnesota...
in Minnesota
Minnesota
Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
and the Rum layered intrusion in Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
.
Occurrence
Skaergaardite is associated with igneous intrusions containing well-preserved, oxide-rich, tholeiitic gabbroGabbro
Gabbro refers to a large group of dark, coarse-grained, intrusive mafic igneous rocks chemically equivalent to basalt. The rocks are plutonic, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
. It is found as inclusions
Inclusion (mineral)
In mineralogy, an inclusion is any material that is trapped inside a mineral during its formation.In gemology, an inclusion is a characteristic enclosed within a gemstone, or reaching its surface from the interior....
in titanian
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
magnetite
Magnetite
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. The chemical IUPAC name is iron oxide and the common chemical name is ferrous-ferric oxide. The formula for magnetite may also be written as FeO·Fe2O3, which is one part...
, ilmenite
Ilmenite
Ilmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-gray. It is a crystalline iron titanium oxide . It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite....
, pyroxenes, and plagioclase
Plagioclase
Plagioclase is an important series of tectosilicate minerals within the feldspar family. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as the plagioclase feldspar series...
. Skaergaardite can occur as an inclusion by itself, but is more commonly found in composite microglobule inclusions of copper iron sulfide mineral
Sulfide mineral
The sulfide minerals are a class of minerals containing sulfide as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, the sulfarsenides and the sulfosalts...
s and other precious metal bearing minerals.
Crystallography and symmetry
The crystallography of skaergaardite was determined using x-ray powder diffraction data. It has an isometric (cubic) crystal systemCubic crystal system
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....
and a hexoctahedral crystal class (Hermann–Mauguin notation: 4/m2/m). Skaergaardite can appear in various forms including: droplets; cubic grains with rounded outlines; euhedral to subhedral grains; and irregular grains or aggregates.
Optical properties
When viewed under a microscope in plane polarized light, skaergaardite appears to be bright creamy white (in the presence of borniteBornite
Bornite is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system .-Appearance:Bornite has a brown to copper-red color on fresh surfaces that tarnishes to various iridescent shades of blue to purple in places...
or chalcopyrite
Chalcopyrite
Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.On exposure to air, chalcopyrite...
) or bright white (in the presence of digenite
Digenite
Digenite is a copper sulfide mineral with formula: Cu9S5. Digenite is a black to dark blue opaque mineral that crystallizes with a trigonal - hexagonal scalenohedral structure. In habit it is usually massive, but does often show pseudo-cubic forms. It has poor to indistinct cleavage and a brittle...
or chalcocite
Chalcocite
Chalcocite, copper sulfide , is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster. It has a hardness of 2½ - 3. It is a sulfide with an orthorhombic crystal system....
). When the mineral is rotated on the microscope stage its color does not change, indicating that it is non-pleochroic.
Under crossed polar light, skaergaardite appears completely dark no matter the direction the stage is rotated, indicating that the mineral is isotropic. As skaergaardite is isotropic, it is also non-birefringent.
Importance
Skaergaardite contains palladiumPalladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
(Pd), one of the six platinum group
Platinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...
metals (PGM) that are some of the rarest elements on earth. With the cost of palladium expected to increase as demand becomes greater, Skaergaardite could begin to be mined for its valuable palladium resources.
The Skaergaard intrusion is the only known source of skaergaardite large enough to be mined. Skaergaardite is the most common PGM mineral in the intrusion, making up over 90% of all the PGM observed. The most mineral rich layer of the intrusion could contain over 1000 tons of skaergaardite. In addition to palladium: gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
, platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
, and other precious metals have been found in the intrusion. Interest has been increasing for an underground mine in the Skaergaard intrusion. A pre-feasibility study is currently under way and is scheduled for completion by December 2011.