Skaergaardite

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Skaergaardite
General
Category Platinum group mineral
Formula
(repeating unit)		PdCu
IMA symbol Skg [1]
Strunz classification 1.AG.30
Crystal system Cubic
Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space group Pm3m
Unit cell a = 3.0014(2) Å
V = 27.0378 Å3, Z = 1
Identification
ColorSteel grey with a bronze tint
Crystal habit Occurs as droplets, equant grains with rounded outlines, subhedral to euhedral crystals, and as irregular grains that vary in size from 2 to 75 micrometers, averaging 22 micrometers.
Tenacity Sectile
Mohs scale hardness4 to 5
Luster Metallic
Streak Black
Diaphaneity Opaque
Specific gravity 10.64
Optical propertiesIsotropic; no discernible internal reflections; color varying from bright creamy white to bright white.
Pleochroism Non-pleochroic
Other characteristicsTypically found in composite microglobules in tholeitic gabbro.
References [2] [3] [4]

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. [3]

Contents

Occurrence

Skaergaardite is associated with igneous intrusions containing well-preserved, oxide-rich, tholeiitic gabbro. 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 minerals and other precious metal bearing minerals. [3]

Crystallography and symmetry

The crystallography of skaergaardite was determined using x-ray powder diffraction data. It has an isometric (cubic) crystal system and a hexoctahedral crystal class (Hermann–Mauguin notation: 4/m32/m). Skaergaardite can appear in various forms including: droplets; cubic grains with rounded outlines; euhedral to subhedral grains; and irregular grains or aggregates. [2] [3]

Optical properties

When viewed under a microscope in plane polarized light, skaergaardite appears to be bright creamy white (in the presence of bornite 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. [3] [5]

Importance

Skaergaardite contains palladium (Pd), one of the six platinum group metals (PGM) that are some of the rarest elements on earth. [6] With the cost of palladium expected to increase as demand becomes greater, Skaergaardite could begin to be mined for its valuable palladium resources. [7]

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. [3] 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. [7] 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. [8]

Related Research Articles

<span class="mw-page-title-main">Palladium</span> Chemical element, symbol Pd and atomic number 46

Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). They have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.

<span class="mw-page-title-main">Bornite</span> Sulfide mineral

Bornite, also known as peacock ore, is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system (pseudo-cubic).

The platinum-group metals are six noble, precious metallic elements clustered together in the periodic table. These elements are all transition metals in the d-block.

<span class="mw-page-title-main">Leucite</span> Potassium and aluminium tectosilicate mineral

Leucite is a rock-forming mineral of the feldspathoid group, silica-undersaturated and composed of potassium and aluminium tectosilicate KAlSi2O6. Crystals have the form of cubic icositetrahedra but, as first observed by Sir David Brewster in 1821, they are not optically isotropic, and are therefore pseudo-cubic. Goniometric measurements made by Gerhard vom Rath in 1873 led him to refer the crystals to the tetragonal system. Optical investigations have since proved the crystals to be still more complex in character, and to consist of several orthorhombic or monoclinic individuals, which are optically biaxial and repeatedly twinned, giving rise to twin-lamellae and to striations on the faces. When the crystals are raised to a temperature of about 500 °C they become optically isotropic and the twin-lamellae and striations disappear, although they reappear when the crystals are cooled again. This pseudo-cubic character of leucite is very similar to that of the mineral boracite.

<span class="mw-page-title-main">Cooperite (mineral)</span> Sulfide mineral

Cooperite is a grey mineral consisting of platinum sulfide, generally in combinations with sulfides of other elements such as palladium and nickel. Its general formula is (Pt,Pd,Ni)S. It is a dimorph of braggite.

<span class="mw-page-title-main">Sperrylite</span>

Sperrylite is a platinum arsenide mineral with the chemical formula PtAs2 and is an opaque metallic tin white mineral which crystallizes in the isometric system with the pyrite group structure. It forms cubic, octahedral or pyritohedral crystals in addition to massive and reniform habits. It has a Mohs hardness of 6 - 7 and a very high specific gravity of 10.6.

<span class="mw-page-title-main">Native metal</span> Form of metal

A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native deposits singly or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, manganese, molybdenum, nickel, niobium, rhenium, selenium, tantalum, tellurium, tin, titanium, tungsten, vanadium, and zinc, as well as the gold group and the platinum group. Among the alloys found in native state have been brass, bronze, pewter, German silver, osmiridium, electrum, white gold, silver-mercury amalgam, and gold-mercury amalgam.

Temagamite is a bright white palladium mercury telluride mineral with a hardness of 2+1⁄2 on the Mohs scale. Its chemical formula is Pd3HgTe3. It was discovered at the Temagami Mine on Temagami Island, Lake Temagami in 1973, and it represents a rare mineral in the Temagami Greenstone Belt.

The Lac des Îles igneous complex of northwestern Ontario, Canada is a layered gabbroic intrusion which is the host for the largest palladium orebody in Canada. The orebody is currently being mined as a combined open pit and underground operation by North American Palladium.

Fletcherite is a rare thiospinel sulfide mineral with formula Cu(Ni,Co)2S4. It is an opaque metallic steel gray mineral which crystallizes in the cubic crystal system. It is a member of the linnaeite group.

<span class="mw-page-title-main">Braggite</span>

Braggite is a sulfide mineral of platinum, palladium and nickel with chemical formula: S. It is a dense, steel grey, opaque mineral which crystallizes in the tetragonal crystal system. It is the central member in the platinum group end-members cooperite and vysotskite.

Louis Jean-Pierre Cabri (born February 23, 1934 in Cairo) is an eminent Canadian scientist in the field of platinum group elements (PGE) mineralogy with expertise in precious metal mineralogy and base metals at the Canada Centre for Mineral and Energy Technology (CANMET). First as Research Scientist and later as Principal Scientist (1996–1999). In the 1970s he discovered two new Cu–Fe sulfide minerals, "mooihoekite" and "haycockite". In 1983 Russian mineralogists named a new mineral after him: cabriite (Pd2SnCu).

Naldrettite is a mineral with a chemical formula of Pd2Sb. It is named after Anthony J. Naldrett (born 1933), a professor at the University of Toronto, who has made significant contributions to the International Mineralogical Association (IMA). Naldrettite is a new intermetallic mineral from the Mesamax Northwest deposit, Ungava region, Québec, Canada. Mineralization takes place around the base of basaltic dyke margins. Naldrettite is economically important because of its chemical composition (Pd2Sb). The sample in which the new mineral was discovered had high platinum group elements (PGEs) with palladium enrichment.

<span class="mw-page-title-main">Gabrielite</span> Sulfosalt mineral

Gabrielite is a rare thallium sulfosalt mineral with a chemical formula of Tl6Ag3Cu6(As,Sb)9S21 or Tl2AgCu2As3S7.

<span class="mw-page-title-main">Nambulite</span>

Nambulite is a lithium bearing manganese silicate mineral with the chemical formula (Li,Na)Mn4Si5O14(OH). It is named after the mineralogist, Matsuo Nambu (born 1917) of Tohoko University, Japan, who is known for his research in manganese minerals. The mineral was first discovered in the Funakozawa Mine of northeastern Japan, a metasedimentary manganese ore.

<span class="mw-page-title-main">Dyscrasite</span> Silver antimonide mineral

The silver antimonide mineral dyscrasite has the chemical formula Ag3Sb. It is an opaque, silver white, metallic mineral which crystallizes in the orthorhombic crystal system. It forms pyramidal crystals up to 5 cm (2.0 in) and can also form cylindrical and prismatic crystals.

Chrisstanleyite, Ag2Pd3Se4, is a selenide mineral that crystallizes in high saline, acidic hydrothermal solution at low temperatures as part of selenide vein inclusions in and alongside calcite veins. It tends to be found in assemblages of other selenides: jagueite, naumannite, fischesserite, oosterboschite, and tiemannite, and it is a solid solution mineral with jagueite Cu2Pd3Se4 in which it shares a unique crystal structure that has not been identified elsewhere (Paar et al. 1998; Nickel 2002; Paar et al. 2004). Chrisstanleyite and jagueite are unlike the other minerals of the selenide family as they do not have a sulfide analogue (Topa et al. 2006). First discovered by Werner Paar from a sample received from Hope's Nose, Torquay, Devon, England, chrisstanleyite has since been discovered in the Pilbara region of Western Australia and in El Chire, La Rioja, Argentina. Chrisstanleyite was named after the Deputy Head and Associate Keeper at the Department of Mineralogy at The Natural History Museum in London.

<span class="mw-page-title-main">Trogtalite</span> Sulfide mineral

Trogtalite is a rare selenide mineral with the formula CoSe2. It crystallizes in the cubic system and is part of the pyrite group, consisting of Co2+ and Se22− ions. It has a rose-violet colour and its crystals are opaque. It often occurs as grains. It was thought to be dimorphous with hastite, but this was discredited in 2009. Hastite turned out to be the iron selenide mineral ferroselite. It forms a solid solution series with krut'aite.

Owensite is a mineral discovered in the Wellgreen Cu-Ni-Pt-Pd deposit, Yukon, with the formula (Ba, Pb)6(Cu, Fe, Ni)25S27. The mineral is related to djerfisherite, but lacks the Cl and monovalent metals found in the latter.

<span class="mw-page-title-main">Ferronickel platinum</span> Rare occurring mineral

Ferronickel platinum is a very rarely occurring minerals from the mineral class of elements (including natural alloys, intermetallic compounds, carbides, nitrides, phosphides and silicides) with the chemical composition Pt2FeNi and thus is chemically seen as a natural alloy, more precisely an intermetallic compound of platinum, nickel and iron in a ratio of 2:1:1.

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 Ralph, J., and Chau, I., "Skaergaardite." Mindat.org. <http://www.mindat.org/min-26980.html>. Accessed 30 September 2010.
  3. 1 2 3 4 5 6 Rudashevsky, N.S., McDonald, A.M., Cabri, L.J., Nielsen, T.F.D., Stanley, C.J., Kretzer, Yu. L., and Rudashevsky, V.N. (2004) Skaergaardite, PdCu, a new platinum-group intermetallic mineral from the Skaergaard intrusion, Greenland. Mineralogical Magazine, 68, 615-632.
  4. ↑ Webmineral data
  5. ↑ Klein, C., and Dutrow, B. (2007) The 23rd Edition of the Manual of Mineral Science. John Wiley and Sons, Inc. Hoboken, New Jersey, U.S.A.
  6. ↑ Powell, D, 2000, "Platinum Group." Mineral Information Institute. <http://www.mii.org/Minerals/photoplat.html>. Accessed 23 November 2010.
  7. 1 2 Brooks, K. (2005) The Skaergaard intrusion: from icon to precious metal deposit. Geology Today, 21, 218-221.
  8. ↑ Platina Resources Limited, 7 October 2009, "Skaergaard Gold-PGM Project Moves To Next Stage Following Positive Scoping Study Review." <http://us-cdn.creamermedia.co.za/assets/articles/attachments/23878_pgm_071009.pdf>. Accessed 23 November 2010.
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